diff --git a/src/problem1.js b/src/problem1.js
index 9a14f2c..5f9c564 100644
--- a/src/problem1.js
+++ b/src/problem1.js
@@ -1,6 +1,51 @@
 function problem1(pobi, crong) {
   var answer;
+  var page = [pobi, crong];
+  var sum = [0, 0];
+  var hundred, ten, one;
+    
+  if (pobi[1] - pobi[0] != 1 || crong[1] - crong[0] != 1){
+      answer = -1;
+      return answer;
+  }
+
+  for (var pageNum = 0; pageNum < page.length; pageNum++){
+    for (var parity = 0; parity < page[pageNum].length; parity++){
+        if (page[pageNum][parity] < 1 || page[pageNum][parity] > 400 || page[pageNum][0] % 2 != 1){
+          answer = -1;
+          return answer;
+        }
+      for (var arithmetic = 0; arithmetic < sum.length; arithmetic++){
+        hundred = Math.trunc(page[pageNum][parity] / 100);
+        ten = Math.trunc(page[pageNum][parity] %100 / 10);
+        one = Math.trunc(page[pageNum][parity] %10);
+          
+        if (arithmetic == 0){
+          if (sum[pageNum] < hundred + ten + one){
+            sum[pageNum] = hundred + ten + one; 
+          }
+        } else {
+          if (hundred == 0){
+              hundred = 1;
+              if (ten == 0){
+                  ten = 1;
+              }
+          }
+          if (sum[pageNum] < hundred * ten * one){
+            sum[pageNum] = hundred * ten * one;
+          }
+        }
+      }
+    }
+  }
+  if (sum[0] > sum[1]){
+    answer = 1;
+  } else if (sum[0] == sum[1]){
+    answer = 0;
+  } else if (sum[0] < sum[1]){
+    answer = 2;
+  }
   return answer;
 }
 
-module.exports = problem1;
+module.exports = problem1;
\ No newline at end of file
diff --git a/src/problem2.js b/src/problem2.js
index cebd07c..cd1c67a 100644
--- a/src/problem2.js
+++ b/src/problem2.js
@@ -1,6 +1,20 @@
 function problem2(cryptogram) {
   var answer;
-  return answer;
+  var text = cryptogram;
+  while (true){
+    answer = text;
+    text = '';
+    for (var loc = 0; loc < answer.length; loc++){
+      if (answer[loc] == answer[loc + 1]){
+        loc += 1;
+        continue;
+      }
+      text += answer[loc];
+    }
+    if (answer == text){
+        return answer
+    }
+  }
 }
 
 module.exports = problem2;
diff --git a/src/problem3.js b/src/problem3.js
index 1baed28..446eb24 100644
--- a/src/problem3.js
+++ b/src/problem3.js
@@ -1,5 +1,13 @@
 function problem3(number) {
   var answer;
+  answer = 0;
+  for (var num = 1; num < number + 1; num++){
+    for (var list of String(num)){
+      if (list == '3' || list == '6' || list == '9'){
+        answer += 1;
+      }
+    }
+  }
   return answer;
 }
 
diff --git a/src/problem4.js b/src/problem4.js
index ee1d3bd..7602a9a 100644
--- a/src/problem4.js
+++ b/src/problem4.js
@@ -1,5 +1,23 @@
 function problem4(word) {
   var answer;
+  answer = '';
+    
+  var code = [0, 0];
+  var startWord = ['A'.charCodeAt(), 'a'.charCodeAt()];
+  var endWord = ['Z'.charCodeAt(), 'z'.charCodeAt()];
+    
+  for (var loc = 0; loc < word.length; loc++){
+    for (var upDown = 0; upDown < code.length; upDown++){
+      code[upDown] = startWord[upDown] + endWord[upDown] - word[loc].charCodeAt(); 
+      if (code[upDown] <= endWord[upDown] && code[upDown] >= startWord[upDown]){
+        answer += String.fromCharCode(code[upDown]);
+        break;
+      }
+      if (upDown == 1){
+        answer += word[loc];
+      }
+    }
+  }
   return answer;
 }
 
diff --git a/src/problem5.js b/src/problem5.js
index 9368e87..8504f76 100644
--- a/src/problem5.js
+++ b/src/problem5.js
@@ -1,5 +1,15 @@
 function problem5(money) {
   var answer;
+  // [5만, 1만, 5천, 1천, 5백, 1백, 5십, 1십, 일]
+  answer = [0, 0, 0, 0, 0, 0, 0, 0, 0];
+  copyMoney = money
+  paper = [50000, 10000, 5000, 1000, 500, 100, 50, 10, 1];
+  for (var count = 0; count < paper.length; count++){
+    if (copyMoney / paper[count] >= 1){
+      answer[count] = Math.trunc(copyMoney / paper[count]);
+      copyMoney = copyMoney % paper[count];
+    }
+  }
   return answer;
 }
 
diff --git a/src/problem6.js b/src/problem6.js
index 3f842b5..d5a5dcb 100644
--- a/src/problem6.js
+++ b/src/problem6.js
@@ -1,5 +1,27 @@
 function problem6(forms) {
   var answer;
+  answer = [];
+  sort = '';
+  for (var member = 0; member < forms.length; member++){
+    for (var word = 0; word < forms[member][1].length - 1; word++){
+      for (var check = 0; check < forms.length; check++){
+        if (member != check){
+          keyword = forms[member][1][word] + forms[member][1][word + 1];
+          if (forms[check][1].indexOf(keyword) !== -1){
+              answer.push(forms[member][0]);
+              break;
+          }
+        }
+      }
+    }
+  }
+  for (var loc = 0; loc < answer.length - 1; loc++){
+    if (answer[loc] > answer[loc + 1]){
+      sort = answer[loc + 1];
+      answer[loc + 1] = answer[loc];
+      answer[loc] = sort;
+    }
+  }
   return answer;
 }
 
diff --git a/src/problem7.js b/src/problem7.js
index ee1bb9d..5b42094 100644
--- a/src/problem7.js
+++ b/src/problem7.js
@@ -1,5 +1,49 @@
 function problem7(user, friends, visitors) {
-  var answer;
+  var answer = [];
+  var relative = [];
+  var score = [];
+  for (var num = 0; num < friends.length; num++){
+    for (var AB = 0; AB < friends[num].length; AB++){
+      if (friends[num][AB] == user){
+        relative.push(friends[num][1 - AB]); 
+      }
+    }
+  }
+  for (var num = 0; num < friends.length; num++){
+    for (var AB = 0; AB < friends[num].length; AB++){
+      friendsLoop:
+      for (var num2 = 0; num2 < relative.length; num2++){
+        if (friends[num][AB] == relative[num2] && friends[num][1 - AB] != user){
+          for (var index = 0; index < score.length; index++){
+            if (score[index][0] == friends[num][1 - AB]){
+              score[index][1] += 10;
+              continue friendsLoop;
+            }
+          }
+          score.push([friends[num][1 - AB], 10]);
+        }
+      }
+    }
+  }
+  visitorsLoop:
+  for (var num = 0; num < visitors.length; num++){
+    if (relative.indexOf(visitors[num]) == -1 && visitors[num] != user){
+      for (var index = 0; index < score.length; index++){
+        if (score[index][0] == visitors[num]){
+          score[index][1] += 1;
+          continue visitorsLoop;
+        }
+      }
+      score.push([visitors[num], 1]);
+    }
+  }
+  for (var index = 0; index < score.length; index++){
+    score[index].sort();
+  }
+  score.sort();
+  for (var result = 0; result < score.length; result++){
+    answer.push(score[result][1]);
+  }
   return answer;
 }