#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
using LL = long long;
using ULL = unsigned long long;

void solve() {
    int x, y;
    cin >> x >> y;
    if (x == 1 || y == 1) {
        cout << "-1" << endl;
    } else {
        cout << "1" << endl;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}