#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef long long LL;
const int N = 1e2 + 2;
const int M = 1e6 + 2;
const int K = 2e6 + 2;
const int INF = 0x3f3f3f3f;
int test, xa, xb, xc, maxx;

signed main() {
    scanf("%lld", &test);
    while (test--) {
        scanf("%lld%lld%lld", &xa, &xb, &xc);
        maxx = max({xa, xb, xc});
        if ((3 * maxx - xa - xb - xc) % 3 == 0) {
            printf("%lld\n", (3 * maxx - xa - xb - xc) / 3);
        } else {
            puts("-1");
        }
    }
    return 0;
}

前 3 个数据都过了，就是最后一个样例怎么没过（结果恰好是两倍）/kk