View Code of Problem 3929

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main (){
	int t, n, m;
	scanf("%d", &t);
	while(t--){
		scanf("%d", &n);
		int sum = 0;
		for(int i = 0;i < n;i++){
			scanf("%d", &m);
			sum ^= m;
		}
		printf("%d\n", sum);
	}

	return 0;
}