View Code of Problem 3929

#include <bits/stdc++.h>
using namespace std;
int main(){

    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        int ans;
        cin>>ans;
        for(int i =1; i<n; i++){
            int x;
            cin>>x;
            ans = ans^x;
        }
        cout<<ans<<endl;
    }
    return 0;
}