#include <bits/stdc++.h>
using namespace std;
int T;
int a, b;
void solve() {
    scanf("%d%d", &a, &b);
    if(a == 1 && b == 1) {
        printf("-1 -1\n");
        return;
    }
    if (a == b) {
        printf("2 %d\n", a);
        return;
    }
    int c = abs(a - b);
    if ((a % 2) == (b % 2)) {
        printf("2 %d\n", c);
    } else {
        if (c >= 2) {
            int minn = 3;
            for(minn = 3; minn * minn <= c; minn += 2) {
                if(c % minn == 0) {
                    break;
                }
            }
            if(minn * minn > c) {
                minn = c;
            }
            printf("%d %d\n", minn, c);
        } else {
            printf("-1 -1\n");
        }
    }
}
int main() {
    scanf("%d", &T);
    while (T--) {
        solve();
    }
    return 0;
}