#include <bits/stdc++.h>
using namespace std;
int mn, mx;
inline void chk(int a, int b, int c) {
    if (c <= b && c >= 2) mn = min(mn, c), mx = max(mx, c);
}
int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int a, b;
        scanf("%d%d", &a, &b);
        if (a > b) swap(a, b);
        int d = b - a;
        if (d) {
            mn = 2e9, mx = -1;
            for (int i = 1; i * i <= d; i++) if (d % i == 0) {
                chk(a, b, i);
                chk(a, b, d / i);
            }
            if (mx == -1) mn = -1;
        } else {
            if (a == 1) mn = mx = -1;
            else mn = 2, mx = a;
        }
        printf("%d %d\n", mn, mx);
    }
    return 0;
}