#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int main()
{
    ll a, b, T;
    scanf("%lld", &T);
    while(T--)
    {
        scanf("%lld%lld", &a, &b);
        ll max_, min_;
        if(a > b)
        {
            max_ = a;
            min_ = b;
        }
        else
        {
            max_ = b;
            min_ = a;
        }
        ll c_max = -1, c_min = -1;
        c_max = max_ - min_;
        ll k = max_ - min_;
        for(ll i=2; i<= ll(sqrt(k * 1.0)) + 1; i++)
        {
            if(k % i ==0)
            {
                c_min = i;
                break;
            }
        }
        if(k >= 2 && c_min == -1)
        {
            c_min = k;
        }
        if(max_ == min_ && max_ >= 2)
        {
            c_max = max_;
            c_min = 2;
        }
        if(c_max != -1 && c_min != -1)
        {
            printf("%lld %lld\n", c_min, c_max);
        }
        else
            printf("-1 -1\n");
    }
    return 0;
}