diff --git "a/week1/3. \353\213\244\354\235\214 \355\201\260 \354\210\253\354\236\220/Solution.java" "b/week1/3. \353\213\244\354\235\214 \355\201\260 \354\210\253\354\236\220/Solution.java"
index 07debf4..aa698e7 100644
--- "a/week1/3. \353\213\244\354\235\214 \355\201\260 \354\210\253\354\236\220/Solution.java"	
+++ "b/week1/3. \353\213\244\354\235\214 \355\201\260 \354\210\253\354\236\220/Solution.java"	
@@ -4,8 +4,47 @@
  */
 class Solution {
 
+    public static void main(String[] args) {
+
+        Solution sol = new Solution();
+
+        System.out.println(sol.solution(78));
+
+    }
+
     public int solution(int n) {
-        int answer = 0;
-        return answer;
+
+        int countOfOne = countOne(n);
+
+        while (countOfOne != countOne(++n)) {
+
+        }
+
+        return n;
+    }
+
+    public int countOne(int n) {
+        int count = 0;
+
+        String binary = Integer.toBinaryString(n);
+
+        for (String number : binary.split("")) {
+            if (number.equals("1")) {
+                count++;
+            }
+        }
+
+        return count;
     }
+
+
+    //문제 풀이를 보는데 거기에서 더 이런식으로도 줄일수 있구나 하면서 보고 있어요 형.. 신기하네요 
+    // public int nextBigNumber(int n) {
+    //     int postPattern = n & -n, smallPattern = ((n ^ (n + postPattern)) / postPattern) >> 2;
+    //     return n + postPattern | smallPattern;
+    // }
+    // public static void main(String[] args) {
+    //     int n = 78;
+    //     System.out.println(new TryHelloWorld().nextBigNumber(n));
+    // }
 }