#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> PII;
const int N = 1e5 + 5, mod = 1e9 + 7;
int T, a, b;
int get(int x) {
    int res = x;
    for(int i = 2; i <= x / i; i++) {
        if(x % i == 0) {
            res = min(res, i);
            break;
        }
    }
    return res;
}
int main() {
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    cin >> T;
    while(T--) {
        cin >> a >> b;
        int c1 = 0, c2 = 0;
        if(a > b) swap(a, b);
        int c = b - a;
        if(!c) {
            c2 = a, c1 = 2;
            if(a == 1) c1 = c2 = -1;
        }
        else if(c == 1) c1 = c2 = -1;
        else c2 = c, c1 = get(c);
        cout << c1 << ' ' << c2 << endl;
    }
    return 0;
}