View Code of Problem 3929

#include <algorithm>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int main(void)
{
    int T;
    int n;
    cin >> T;
    while(T--){
        cin >> n;
        int sum, tmp;
        cin >> sum;
        while(--n){
            cin >> tmp;
            sum ^= tmp;
        }
        cout << sum << endl;
    }
}