#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sc(x) scanf("%lld",&(x));
#define pb push_back
#define fi first
#define se second


signed main()
{
    int t;
    sc(t)
    int a, b;
    vector<int> vec;
    while(t--)
    {
        sc(a)sc(b)
        vec.clear();
        if(a == b){
                if(a == 1){
                    cout << -1 << ' '<< -1 << '\n';

                }else{
                    cout << 2 << ' ' << a << '\n';
                }
                continue;
        }
        int c = abs(a - b);
        int x = -1;
        int y = -1;
        if(c != 1)
        {
            for(int i = 1; i*i <= c; i++)
            {
                if(c % i == 0)
                {
                    if(i != 1){
                        vec.pb(i);
                    }
                    if((c/i) != 1){
                        vec.pb(c/i);
                    }
                }
            }
        }
        if(vec.size()){
            sort(vec.begin(),vec.end());
            x = vec[0];
            y = vec[vec.size() - 1];
        }
        cout << x << ' ' << y<<'\n';
    }
}