#include <bits/stdc++.h>
#define int long long

using namespace std;

int n;

signed main() {
    cin >> n;
    for (int i = 1; i <= n; i ++) {
        int a, b;
        cin >> a >> b;
        int p = labs(a - b);
        if (p == 1 || max(a, b) < 2)
            cout << "-1 -1" << endl;
        else {
            int ans1 = 0;
            bool init = 0;
            for (int i = 2; i * i <= p; i ++)
                if (p % i == 0) {
                    ans1 = i;
                    init = 1;
                    break;
                }
            if (init == 0) ans1 = p;
            if (a != b) cout << ans1 << ' ' << p << endl;
            else cout << 2 << ' ' << a << endl;
        }
    }
}