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


int main()
{
    int n;
	cin >> n;
	for (int i = 0; i < n; i++){
		int x, y;
		cin >> x; cin >> y;
		cout << ((x == 1 || y == 1) ? -1: 1) << endl;
	}
	return 0;
}