diff --git a/Easy/Day 21/solution.cpp b/Easy/Day 21/solution.cpp
index 2084d29..dac9aa6 100644
--- a/Easy/Day 21/solution.cpp	
+++ b/Easy/Day 21/solution.cpp	
@@ -1 +1,15 @@
-// Write your code here.
\ No newline at end of file
+// Write your code here.
+#include <bits/stdc++.h>
+using namespace std;
+int main(){
+    int n;
+    cin >> n;
+    int sum = 0;
+    for(int i = 0 ;  i< (4*n)-1 ; i++){
+        int temp;
+        cin >> temp;
+        sum = sum ^ temp;
+    }
+    cout << sum;
+    return 0;
+}
\ No newline at end of file