#include <set>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define LL long long

template <typename T>
void read (T &x) {
    x = 0; T f = 1;
    char ch = getchar ();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar ();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar ();
    }
    x *= f;
}
template <typename T>
void write (T x) {
    if (x < 0) { x = -x; putchar ('-'); }
    if (x < 10) { putchar (x + '0'); return; }
    write (x / 10);
    putchar (x % 10 + '0');
}
template <typename T> void print (T x, char ch) { write (x); putchar (ch); }
template <typename T> T Min (T x, T y) { return x < y ? x : y; }
template <typename T> T Max (T x, T y) { return x > y ? x : y; }
template <typename T> T Abs (T x) { return x > 0 ? x : -x; }

int t;
LL a, b;

int main () {
    read (t);
    while (t--) {
        read (a); read (b); if (a > b) swap (a, b);
        
        if (a == b) {
            if (a == 1) printf ("-1 -1\n");
            else printf ("2 %lld\n", a);
            continue;
        }
        
        LL _max, _min;
        _max = _min = b - a;
        for (LL i = 2; i * i <= _max; i++) {
            if (_max % i == 0) {
                _min = i;
                break;
            }
        }
        if (_min == 1) printf ("-1 -1\n");
        else printf ("%lld %lld\n", _min, _max);
    }
    return 0;
}