#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int tt;
    cin >> tt;
    while (tt--) {
        int a, b;
        cin >> a >> b;
        if (a > b) {
            swap(a, b);
        }
        if (b - a == 1 || b == 1) {
            cout << -1 << " " << -1 << '\n';
            continue;
        }
        int c = b - a;
        if (c == 0) {
            cout << 2 << " " << a << '\n';
            continue;
        }
        int d = c;
        for (int i = 2; i * i <= c; i++) {
            if (c % i == 0) {
                d = i;
                break;
            }
        }
        cout << d << " " << c << '\n';
    }
    return 0;
}