diff --git a/build.gradle.kts b/build.gradle.kts
new file mode 100644
index 0000000..31f6093
--- /dev/null
+++ b/build.gradle.kts
@@ -0,0 +1,32 @@
+plugins {
+    id("java")
+}
+
+group = "com.vitekkor"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation(platform("org.junit:junit-bom:5.9.1"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_21
+    targetCompatibility = JavaVersion.VERSION_21
+}
+
+tasks.compileJava {
+    options.compilerArgs.add("--enable-preview")
+}
+
+tasks.compileTestJava {
+    options.compilerArgs.add("--enable-preview")
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..7f93135
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..3fa8f86
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..1aa94a4
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC2039,SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..93e3f59
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle.kts b/settings.gradle.kts
new file mode 100644
index 0000000..c1ca85e
--- /dev/null
+++ b/settings.gradle.kts
@@ -0,0 +1,2 @@
+rootProject.name = "kotoed"
+
diff --git a/src/main/java/com/vitekkor/kotoed/HomeWork.java b/src/main/java/com/vitekkor/kotoed/HomeWork.java
new file mode 100644
index 0000000..114d5d0
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/HomeWork.java
@@ -0,0 +1,9 @@
+package com.vitekkor.kotoed;
+
+import java.time.Instant;
+
+public record HomeWork(
+        int name,
+        Instant deadline
+) {
+}
diff --git a/src/main/java/com/vitekkor/kotoed/HomeWorkResult.java b/src/main/java/com/vitekkor/kotoed/HomeWorkResult.java
new file mode 100644
index 0000000..7c5ddfc
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/HomeWorkResult.java
@@ -0,0 +1,7 @@
+package com.vitekkor.kotoed;
+
+public record HomeWorkResult(
+        int mark,
+        HomeWork homeWork
+) {
+}
diff --git a/src/main/java/com/vitekkor/kotoed/Kotoed.java b/src/main/java/com/vitekkor/kotoed/Kotoed.java
new file mode 100644
index 0000000..e3fcf66
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/Kotoed.java
@@ -0,0 +1,43 @@
+package com.vitekkor.kotoed;
+
+import java.util.Comparator;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.PriorityBlockingQueue;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class Kotoed {
+    private final PriorityBlockingQueue<HomeWork> queue
+            = new PriorityBlockingQueue<>(10, Comparator.comparing(HomeWork::deadline));
+
+    private final ConcurrentHashMap<Integer, HomeWorkResult> results = new ConcurrentHashMap<>();
+
+    public void checkHomeWork(Worker worker) throws InterruptedException {
+        while (true) {
+            System.out.println("Worker #" + worker.getWorkerId() + " waits for new homework");
+            var homeWork = queue.take();
+
+            System.out.println("Worker #" + worker.getWorkerId() + " start checking homework: " + homeWork.name() + "due to " + homeWork.deadline());
+            worker.setWorking(true);
+            Thread.sleep(2000);
+            System.out.println("Worker #" + worker.getWorkerId() + " finish checking homework: " + homeWork.name());
+            var mark = ThreadLocalRandom.current().nextInt(0, 11);
+            results.put(homeWork.name(), new HomeWorkResult(mark, homeWork));
+            worker.setWorking(false);
+        }
+    }
+
+    public void submitHomeWork(int id, HomeWork homeWork) {
+        System.out.println("Student #" + id + " submit new homework: " + homeWork.name());
+        queue.add(homeWork);
+    }
+
+    public HomeWorkResult getHomeWorkResult(int id, int name) throws InterruptedException {
+        while (results.get(name) == null) {
+            System.out.println("Student #" + id + " waits for homework result");
+            Thread.sleep(1000);
+        }
+        var result = results.get(name);
+        System.out.println("Student #" + id + " received the result: " + result);
+        return result;
+    }
+}
diff --git a/src/main/java/com/vitekkor/kotoed/Simulation.java b/src/main/java/com/vitekkor/kotoed/Simulation.java
new file mode 100644
index 0000000..4e9c3ec
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/Simulation.java
@@ -0,0 +1,28 @@
+package com.vitekkor.kotoed;
+
+import java.util.Arrays;
+
+public class Simulation {
+    public static void main(String[] args) throws InterruptedException {
+        var kotoed = new Kotoed();
+        Worker[] workers = new Worker[10];
+        for (int i = 0; i < 10; i++) {
+            workers[i] = new Worker(kotoed, i);
+            workers[i].start();
+        }
+
+        for (int i = 0; i < 100; i++) {
+            var student = new Student(kotoed, i);
+            student.start();
+        }
+
+        while (Arrays.stream(workers).anyMatch(Worker::isWorking)) {
+            System.out.println("waits for completion");
+            Thread.sleep(1000);
+        }
+        for (Worker worker : workers) {
+            worker.interrupt();
+        }
+        System.out.println("Done.");
+    }
+}
diff --git a/src/main/java/com/vitekkor/kotoed/Student.java b/src/main/java/com/vitekkor/kotoed/Student.java
new file mode 100644
index 0000000..0b0c312
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/Student.java
@@ -0,0 +1,40 @@
+package com.vitekkor.kotoed;
+
+import java.time.Instant;
+import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class Student extends Thread {
+
+    private final Instant startInclusive = Instant.now().minusSeconds(10000L);
+    private final Instant endExclusive = startInclusive.plusSeconds(10000L * 2L);
+
+    private final Kotoed kotoed;
+    private final int id;
+
+    public Student(Kotoed kotoed, int id) {
+        this.kotoed = kotoed;
+        this.id = id;
+    }
+
+    @Override
+    public void run() {
+        var newHomeWork = new HomeWork(new Random().nextInt(), randomDate(startInclusive, endExclusive));
+        kotoed.submitHomeWork(id, newHomeWork);
+        try {
+            kotoed.getHomeWorkResult(id, newHomeWork.name());
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+    }
+
+    public static Instant randomDate(Instant startInclusive, Instant endExclusive) {
+        long startSeconds = startInclusive.getEpochSecond();
+        long endSeconds = endExclusive.getEpochSecond();
+        long random = ThreadLocalRandom
+                .current()
+                .nextLong(startSeconds, endSeconds);
+
+        return Instant.ofEpochSecond(random);
+    }
+}
diff --git a/src/main/java/com/vitekkor/kotoed/Worker.java b/src/main/java/com/vitekkor/kotoed/Worker.java
new file mode 100644
index 0000000..12bebfe
--- /dev/null
+++ b/src/main/java/com/vitekkor/kotoed/Worker.java
@@ -0,0 +1,35 @@
+package com.vitekkor.kotoed;
+
+public class Worker extends Thread {
+    private final Kotoed kotoed;
+
+    public int getWorkerId() {
+        return id;
+    }
+
+    private final int id;
+
+    public boolean isWorking() {
+        return isWorking;
+    }
+
+    public void setWorking(boolean working) {
+        isWorking = working;
+    }
+
+    private boolean isWorking = false;
+
+    public Worker(Kotoed kotoed, int id) {
+        this.kotoed = kotoed;
+        this.id = id;
+    }
+
+    @Override
+    public void run() {
+        try {
+            kotoed.checkHomeWork(this);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+        }
+    }
+}