#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <stack>
#define PI acos(-1.0)
#define CLR(a, b) memset(a, (b), sizeof(a))
#define fi first
#define se second
#define ll o<<1
#define rr o<<1|1
using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
const int MAXN = 4*1e3+10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
void add(LL &x, LL y) { x += y; x %= MOD; }
int main()
{
    int t; scanf("%d", &t);
    while(t--) {
        int n; scanf("%d", &n); int v;
        for(int i = 0; i < n; i++) {
            scanf("%d", &v);
        }
        if(n == 1) {
            printf("%d\n", v);
        }
        else {
            printf("0\n");
        }
    }
    return 0;
}