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

#define vi vector<int>
#define PB push_back
#define vll vector<long long>
#define ll long long
#define all(x) x.begin(), x.end()
#define F first
#define S second
#define ld long double
#define vld vector<long double>

const ll mod = 998244353;
const ll MOD = 1e9 + 7;

void solve(int tst){
    
    ll a, b;
    cin >> a >> b;

    if (min(a, b) > 1){
        cout << "1\n";
    }
    else {
        cout << "-1\n";
    }

}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    // pre();
    int tc = 1;
    cin >> tc;
    for (int i = 1; i <= tc; i++){
        solve(i);
    }
    return 0;
}