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

typedef long long ll;

int T;
int main () {
    //freopen("out.txt", "r", stdin);
    cin >> T;
    while (T --){
        ll s, t, a;
        cin >> s >> t;
        a = abs(s - t);
        ll mx = -1, mi = -1;
        if (a >= 2){ 
            mi = a;
            for (ll i = 2; i * i <= a; i ++)
                if (a % i == 0){
                    mx = i;
                    break;
                }
            if (mx == - 1) mx = mi;
        }else if (a == 0){
            mx = min(s, t);
            mi = max(s, t);
            if (mi >= 2) mx = 2;
        }
        if (mi < 2 || mi < 2) mi = -1, mx = - 1;
        cout << mx << ' ' << mi << endl;
    }
    return 0;
}