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..88b81df 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"	
@@ -2,7 +2,7 @@
  * 3. 다음 큰 숫자
  * https://programmers.co.kr/learn/courses/30/lessons/12911
  */
-class Solution {
+class Solution3 {
 
     public int solution(int n) {
         int answer = 0;
diff --git "a/week1/5. \354\206\214\354\210\230 \353\247\214\353\223\244\352\270\260/Solution.java" "b/week1/5. \354\206\214\354\210\230 \353\247\214\353\223\244\352\270\260/Solution.java"
index cae8dac..d1367c1 100644
--- "a/week1/5. \354\206\214\354\210\230 \353\247\214\353\223\244\352\270\260/Solution.java"	
+++ "b/week1/5. \354\206\214\354\210\230 \353\247\214\353\223\244\352\270\260/Solution.java"	
@@ -3,14 +3,49 @@
     https://programmers.co.kr/learn/courses/30/lessons/12915
 
 */
-class Solution {
+class Solution5 {
+
+    public static void main(String[] args) {
+
+        Solution5 sol1 = new Solution5();
+
+        int[] nums = { 1, 2, 7, 6, 4 };
+
+        System.out.println(sol1.solution(nums));
+    }
 
     public int solution(int[] nums) {
-        int answer = -1;
+        int numsLength = nums.length;
+
+        int primeNumberCount = 0;
+
+        for (int i = 0; i < numsLength - 2; i++) {
+            for (int j = i + 1; j < numsLength - 1; j++) {
+                for (int k = j + 1; k < numsLength; k++) {
+
+                    int total = nums[i] + nums[j] + nums[k];
+                    if (checkPrimeNumber(total)) {
+                        primeNumberCount++;
+                    }
+                }
+            }
+        }
+
+        return primeNumberCount;
+    }
+
+    public boolean checkPrimeNumber(int number) {
+
+        boolean checkPrime = true;
 
-        System.out.println("Hello Java");
+        for (int i = 2; i <= Math.sqrt(number); i++) {
+            if (number % i == 0) {
+                checkPrime = false;
+                return checkPrime;
+            }
+        }
 
-        return answer;
+        return checkPrime;
     }
 
 }