diff --git a/20210818/BOJ13567.java b/20210818/BOJ13567.java
new file mode 100644
index 0000000..dba19c1
--- /dev/null
+++ b/20210818/BOJ13567.java
@@ -0,0 +1,61 @@
+package day1.robot;
+// https://www.acmicpc.net/problem/13567
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class BOJ13567 {
+    static int M, N;
+    static int dx[] = { 1, 0, -1, 0 }; // 동남서북
+    static int dy[] = { 0, -1, 0, 1 };
+
+
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        M = Integer.parseInt(st.nextToken());
+        N = Integer.parseInt(st.nextToken());
+
+        String action;
+        int num;
+        int x=0; int y=0;
+        int dir =0;
+
+        for(int i=0; i< N; i++) {
+            StringTokenizer st2 = new StringTokenizer(br.readLine());
+
+            action = st2.nextToken();
+            num = Integer.parseInt(st2.nextToken());
+
+
+            if(action.equals("MOVE")) {
+                x += dx[dir]*num;
+                y += dy[dir]*num;
+                if(ifOut(x,y,M)){
+                    System.out.println(-1);
+                    return;
+                }
+            }
+            else if(action.equals("TURN")) {
+                if(num==0){
+                    dir = (dir + 4-1)%4;
+                }
+                else{
+                    dir = (dir+1)%4;
+                }
+            }
+
+
+        }
+
+        System.out.println(x+" "+y);
+
+    }
+
+    public static boolean ifOut(int x, int y, int m) {
+        return x>=m || y>=m || x<0 || y<0;
+    }
+}
diff --git a/20210818/BOJ14467.java b/20210818/BOJ14467.java
new file mode 100644
index 0000000..20a9d31
--- /dev/null
+++ b/20210818/BOJ14467.java
@@ -0,0 +1,29 @@
+package day1;
+// https://www.acmicpc.net/problem/14467
+import java.util.Arrays;
+import java.util.Scanner;
+
+public class BOJ14467 {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int ansewer =0;
+        int all = sc.nextInt();
+        int[] cow = new int[11];
+        Arrays.fill(cow,-1);
+        int key; int cross;
+
+        for(int i=0;i<all;i++) {
+            key = sc.nextInt();
+            cross = sc.nextInt();
+
+            if(cow[key]==-1) cow[key] = cross;
+            else if(cow[key] != cross){
+                ansewer += 1;
+                cow[key] = cross;
+            }
+        }
+        System.out.println(ansewer);
+
+
+    }
+}
diff --git a/20210818/BOJ2870.java b/20210818/BOJ2870.java
new file mode 100644
index 0000000..3cc2fae
--- /dev/null
+++ b/20210818/BOJ2870.java
@@ -0,0 +1,32 @@
+package bjon2870;
+//https://par3k.tistory.com/86
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Collections;
+
+public class BOJ2870 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+        ArrayList<BigInteger> answer = new ArrayList<>();
+        String[] line;
+
+        for(int i=0;i<N;i++) {
+            line = br.readLine().split("\\D");
+            for(int j=0;j<line.length;j++) {
+                if(!line[j].equals("")) answer.add(new BigInteger(line[j]));
+            }
+        }
+        Collections.sort(answer);
+
+        for(int i=0;i<answer.size();i++) {
+            System.out.println(answer.get(i));
+        }
+
+    }
+}
diff --git a/20210818/BOJ3048.java b/20210818/BOJ3048.java
new file mode 100644
index 0000000..f19bbc7
--- /dev/null
+++ b/20210818/BOJ3048.java
@@ -0,0 +1,68 @@
+package day1.ant;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class BOJ3048 {
+    public static void main(String[] args) throws IOException {
+
+        System.out.println("입력 : ");
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int a1 = Integer.parseInt(st.nextToken());
+        int a2 = Integer.parseInt(st.nextToken());
+
+        char[] ant1 = new char[a1];
+        char[] ant2;
+
+        String str = br.readLine();
+
+        for(int i=0;i<a1;i++) {
+            ant1[i] = str.charAt(a1-1- i);
+        }
+
+        ant2 = br.readLine().toCharArray();
+
+        char[] all_ant = new char[a1 + a2];
+        int[] idx = new int[a1 + a2];
+
+        for(int i=0; i<all_ant.length;i++) {
+            if(i<a1) {
+                all_ant[i] = ant1[i];
+                idx[i] = 0;
+            }
+            else {
+                all_ant[i] = ant2[i - a1];
+                idx[i] = 1;
+            }
+        }
+
+        int cnt = Integer.parseInt(br.readLine());
+        char tmp;
+        int idx_tmp;
+
+        while(cnt>0){
+            cnt--;
+            for(int i=0;i<all_ant.length-1;i++){
+                if(idx[i]==0&&idx[i+1]==1) {
+                    tmp = all_ant[i];
+                    all_ant[i] = all_ant[i + 1];
+                    all_ant[i + 1] = tmp;
+                    idx_tmp = idx[i];
+                    idx[i] = idx[i + 1];
+                    idx[i+1] = idx_tmp;
+                    i++;
+                }
+            }
+
+        }
+
+        for (char c : all_ant) {
+            System.out.print(c);
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/20210818/BOJ4659.java b/20210818/BOJ4659.java
new file mode 100644
index 0000000..75829d7
--- /dev/null
+++ b/20210818/BOJ4659.java
@@ -0,0 +1,77 @@
+package bjon4659;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class BOJ4659 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        String tmp;
+
+        while(!(tmp=br.readLine()).equals(("end"))){
+
+            if(total(tmp))
+                System.out.println("<"+tmp+">"+" is acceptable.");
+            else
+                System.out.println("<"+tmp+">"+" is not acceptable.");
+
+
+        }
+    }
+    static boolean total(String tmp){
+        if(rule_vowel(tmp)){
+            if(rule_chain(tmp)){
+                if(rule_same(tmp))
+                    return true;
+            }
+        }
+        return false;
+    }
+
+    static boolean rule_vowel_ch(char ch) {
+        if(ch=='a'|| ch=='e' || ch=='i' || ch=='o' || ch=='u')
+            return true;
+        return false;
+    }
+
+
+    static boolean rule_vowel(String tmp) {
+
+        for(int i=0;i<tmp.length();i++) {
+            if(rule_vowel_ch(tmp.charAt(i)))
+                return true;
+        }
+        return false;
+    }
+
+    static boolean rule_chain(String tmp) {
+        int mcnt =0; int jcnt=0;
+        for(int i=0;i<tmp.length();i++) {
+            if(rule_vowel_ch(tmp.charAt(i))) {
+                mcnt++;
+                jcnt = 0;
+            }
+            else {
+                jcnt++;
+                mcnt = 0;
+            }
+            if(mcnt==3 || jcnt==3)
+                return false;
+        }
+        return true;
+
+    }
+
+    static boolean rule_same(String tmp) {
+        if(tmp.length()>1){
+            for(int i=0; i<tmp.length()-1;i++){
+                if(tmp.charAt(i)==tmp.charAt(i+1)){
+                    if(tmp.charAt(i)!='e'&& tmp.charAt(i)!='o')
+                        return false;
+                }
+            }
+        }
+        return true;
+    }
+}
diff --git a/20210818/BOJ5635.java b/20210818/BOJ5635.java
new file mode 100644
index 0000000..03c084b
--- /dev/null
+++ b/20210818/BOJ5635.java
@@ -0,0 +1,44 @@
+package day1.birthday;
+
+
+import java.io.IOException;
+import java.util.Scanner;
+
+
+class BOJ5635 {
+    public static void main(String[] args) throws IOException {
+
+
+        Scanner scan = new Scanner(System.in);
+
+        int nums = Integer.parseInt(scan.nextLine());
+
+        int max = Integer.MAX_VALUE;
+        int min = Integer.MIN_VALUE;
+
+        String minNA = "";
+        String maxNA = "";
+
+        for(int i=0;i<nums;i++) {
+            String exNa = scan.next();
+            int day = 0;
+            day += Integer.parseInt(scan.next());
+            day += Integer.parseInt(scan.next())* 100;
+            day += Integer.parseInt(scan.next()) * 10000;
+
+
+            if(min<day) {
+                min = day;
+                minNA = exNa;
+            }
+            else if (max>day) {
+                max = day;
+                maxNA = exNa;
+            }
+        }
+
+        System.out.println(minNA);
+        System.out.println(maxNA);
+
+        }
+}
diff --git a/20210818/BOJ7785.java b/20210818/BOJ7785.java
new file mode 100644
index 0000000..4ad2209
--- /dev/null
+++ b/20210818/BOJ7785.java
@@ -0,0 +1,38 @@
+package bjon7785;
+// https://www.acmicpc.net/problem/7785
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+
+public class BOJ7785 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int num = Integer.parseInt(br.readLine());
+        StringTokenizer st;
+        ArrayList<String> answer = new ArrayList<>();
+
+        Map<String, String> map = new HashMap<>();
+
+
+
+        for(int i=0; i<num; i++) {
+            st = new StringTokenizer(br.readLine());
+            String name = st.nextToken();
+            String state = st.nextToken();
+
+            map.put(name, state);
+        }
+
+        for(String key : map.keySet()) {
+            if(map.get(key).equals("enter")) answer.add(key);
+        }
+        Collections.sort(answer, Collections.reverseOrder());
+
+        for(int i=0; i<answer.size();i++) {
+            System.out.println(answer.get(i));
+        }
+
+    }
+}
diff --git a/20210818/Weekly_2th.java b/20210818/Weekly_2th.java
new file mode 100644
index 0000000..8564b01
--- /dev/null
+++ b/20210818/Weekly_2th.java
@@ -0,0 +1,6 @@
+package day1.weekly2;
+
+public class Weekly_2th {
+    // https://programmers.co.kr/learn/courses/30/lessons/83201?language=java
+
+}
diff --git a/20210825/BOJ2644.java b/20210825/BOJ2644.java
new file mode 100644
index 0000000..927958e
--- /dev/null
+++ b/20210825/BOJ2644.java
@@ -0,0 +1,70 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class BOJ2644 {
+
+    static int num;
+    static int start,end;
+    static List<Integer>[] graph;
+    static boolean[] visit;
+    static Queue<Integer> queue;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+        num = Integer.parseInt(br.readLine());  // 총 인구 받기
+        st = new StringTokenizer(br.readLine());  //2번째 입력값 나누기
+        start = Integer.parseInt(st.nextToken()); // 첫째 사람
+        end = Integer.parseInt(st.nextToken()); // 둘째 사람
+        int M = Integer.parseInt(br.readLine()); // 총 촌수 관계 숫자 받기
+
+
+        graph = new ArrayList[num+1]; // 사람 리스트 만들기 -> 0을 제외하기 위해 (num+1)
+        for(int i=1;i<=num;i++){   // i=1 -> 0인 사람이 없기 때문에
+            graph[i]=new ArrayList<>(); //   사람 별 리스트 생성
+        }
+
+
+        for(int i=0;i<M;i++) {  // 각 해당 사람에 대한 관계있는 사람들 리스트 주입
+            st=new StringTokenizer(br.readLine());
+            int parents=Integer.parseInt(st.nextToken());
+            int child=Integer.parseInt(st.nextToken());
+            graph[parents].add(child);
+            graph[child].add(parents);
+        }
+        System.out.println(Bfs(start,end));
+
+    }
+
+    private static int Bfs(int start, int end) {  //너비 우선 탐색 사용 (BFS)
+        int answer=0;
+        visit = new boolean[num+1];  // 방문 여부 리스트 (dafualt : false 로 생성)
+        queue = new LinkedList<Integer>();  // 연결된 노드
+
+        visit[start] = true;
+        queue.offer(start);
+
+        while (!queue.isEmpty()) {
+            int queueSize = queue.size();
+            for(int i=0;i<queueSize;i++){  // 기준 노드에서 연결된 노드 방문 반복문
+                int now = queue.poll();
+                if (now == end)
+                    return answer;
+
+                for (int next : graph[now]) {
+                    if (!visit[next]) {    // 해당 노드가 false이면 (방문한 적이 없으면)
+                        queue.offer(next);  // 연결 노드 queue에 삽입
+                        visit[next] = true;
+                    }
+                }
+            }
+
+            answer++;
+        }
+
+
+        return -1;  // start 와 end 가 연결되지 않았을 경우
+    }
+}
diff --git a/20210902/BOJ6118.java b/20210902/BOJ6118.java
new file mode 100644
index 0000000..675fa5b
--- /dev/null
+++ b/20210902/BOJ6118.java
@@ -0,0 +1,83 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+
+public class BOJ6118 {
+    static int N, M;
+    static List<Integer>[] graph;
+    static boolean[] visit;
+    static Queue<Integer> queue;
+    static int[] dist;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+        st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken()); // 헛간 개수
+        M = Integer.parseInt(st.nextToken()); //  연결 개수
+
+        graph = new ArrayList[N + 1];
+        for (int i = 1; i <= N; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        int a_i, b_i = 0;
+
+        for (int i = 0; i < M; i++) {   // 헛간간의 관계 리스트 생성
+            st = new StringTokenizer(br.readLine());
+            a_i = Integer.parseInt(st.nextToken());
+            b_i = Integer.parseInt(st.nextToken());
+            graph[a_i].add(b_i);
+            graph[b_i].add(a_i);
+        }
+
+        Bfs(1);
+
+    }
+
+    private static void Bfs(int start) {
+
+        visit = new boolean[N + 1];   // 방문 여부 배열
+        queue = new LinkedList<Integer>(); // BFS 를 위한 큐
+        dist = new int[N+1]; // 0에서 해당 헛간간의 거리 배열
+
+        // 초기화
+        visit[start] = true;
+        queue.offer(start);
+        Arrays.fill(dist, 0);
+
+        //BFs 탐색
+        while (!queue.isEmpty()) {
+
+            int now = queue.poll();
+
+            for (int next : graph[now]) {
+                if (!visit[next]) {
+                    queue.offer(next);
+                    visit[next] = true;
+                    dist[next] = dist[now] +1;
+                }
+            }
+        }
+
+        int maxPlace = Integer.MIN_VALUE; //숨은 헛간 번호
+        int maxDist = Integer.MIN_VALUE; // 숨은 헛간 거리
+        int maxNum = 1; // 숨은 헛간과 같은 거리를 갖는 헛간의 개수
+
+        // ditst[] 배열 탐색
+        for (int i = 1; i <= N; i++) {
+            if (maxDist < dist[i]) {
+                maxDist = dist[i];
+                maxPlace = i;
+                maxNum = 1;
+            } else if (maxDist == dist[i]) {
+                maxNum++;
+            }
+        }
+        System.out.println(maxPlace + " " + maxDist + " " + maxNum);
+
+    }
+}
diff --git a/20210902/READ.MD b/20210902/READ.MD
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/20210902/READ.MD
@@ -0,0 +1 @@
+
diff --git a/20210909/BOJ19940.java b/20210909/BOJ19940.java
new file mode 100644
index 0000000..4d84aea
--- /dev/null
+++ b/20210909/BOJ19940.java
@@ -0,0 +1,61 @@
+import java.io.*;
+
+public class BOJ19940 {
+
+    static int N,M;
+    static int sixty, ten, one;
+    static int[] answer;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+
+        N = Integer.parseInt(br.readLine());  // 반복 횟수
+
+
+
+        for (int i = 0; i < N; i++) {
+            M = Integer.parseInt(br.readLine());  // 입력값
+            answer = new int[5];  // 정답 배열 => +60 , +10, -10, +1, -1
+
+            sixty = M / 60;
+            ten = (M % 60) / 10;
+            one = M % 10;
+
+            if(one >5){
+                ten += 1;
+                one -= 10;
+            }
+
+            if (ten > 3) {
+                sixty += 1;
+                ten -= 6;
+            }
+            if (one == 5 && ten<0) {   // 45, 55의 예외적인 경우
+                ten += 1;
+                one -= 10;
+            }
+
+
+            answer[0] = sixty;
+            if(ten>0) answer[1] = ten;
+            if(ten<0) answer[2] = Math.abs(ten);
+            if(one>0) answer[3] = one;
+            if(one<0) answer[4] = Math.abs(one);
+
+            for(int j = 0 ; j < 5 ; j++) bw.write(answer[j] + " ");
+            bw.write("\n");
+            bw.flush();
+
+
+        }
+
+
+
+
+
+
+
+
+    }
+}
diff --git a/20210916/BOJ2468.java b/20210916/BOJ2468.java
new file mode 100644
index 0000000..d7fe6d1
--- /dev/null
+++ b/20210916/BOJ2468.java
@@ -0,0 +1,76 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+//https://www.acmicpc.net/problem/2468
+// 18476KB	252ms
+public class BOJ2468 {
+
+    static int[][] map;
+    static int N;
+    static boolean[][] visit;
+    static int[] dx = {0, 0, -1, 1};
+    static int[] dy = {-1, 1, 0, 0};
+
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = null;
+
+        N = Integer.parseInt(br.readLine()); // 행,열의 수
+        int max = 0;
+        map = new int[N+1][N+1];
+
+        for (int i = 0; i < N; i++) {  // 입력값을 통해 각 영역 높이를 배열로 표현
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < N; j++) {
+                map[i][j] = Integer.parseInt(st.nextToken());
+                max = Math.max(max, map[i][j]);   // 가장 높은 영역의 높이 |편리하다
+            }
+        }
+
+
+
+        int ans = 0;
+
+
+
+        for (int sea = 1; sea <= max; sea++) {  // 1부터 가장 높은 높이 까지 물이 차오르는 조건 설정
+            visit = new boolean[N + 1][N + 1];  // 방문처리를 위한 배열
+            int cnt = 0;
+            for (int x = 0; x < N; x++) {
+                for (int y =0; y < N; y++) {
+                    if(map[x][y]>sea && !visit[x][y]){   // 방문을 하지 않았거나 해수면보다 높은 영역 탐색
+                        cnt++;   // 해당 해수면 높이에 따른 영역 개수 => 재귀함수를 돌면서 상하좌우로 연결된 노드들은 하나로 카운트
+                        dfs(sea,x,y);  // 해수면 높이, map 좌표
+                    }
+                }
+            }
+            //System.out.println(cnt);
+            ans = Math.max(ans, cnt);   // 여러 해수면 높이중 가장 높은 영역 횟수 구하기
+        }
+
+        System.out.println(ans==0 ? 1:ans);  // 아무 지역도 물에 잠기지 않을수 있다가 밑에 조그만하게 적혀있었음 / 람다식 한번 써봄
+    }
+   static void dfs(int sea, int x, int y) {
+       visit[x][y] =true;  // 방문처리
+
+       for (int i = 0; i < 4; i++) {
+            int nx = x + dx[i];  // 좌우
+            int ny = y + dy[i];  // 상하
+
+           //기준 좌표에서 상하좌우에 있는 노드 탐색
+            if (nx >= 0 && ny >= 0 && nx < N && ny < N) {  // 좌표 평면을 벗어나지 않는 노드
+                if(!visit[nx][ny] && map[nx][ny]>sea){  // 방문한적 없고 해수면 높이보다 높은 노드
+                    dfs(sea,nx,ny);  // 재귀 호출 => 위의 조건을 만족하는 상하좌우의 노드들을 계속해서 탐색
+                }
+
+            }
+        }
+
+    }
+
+
+}
+
diff --git a/20210916/READ.MD b/20210916/READ.MD
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/20210916/READ.MD
@@ -0,0 +1 @@
+