#include <iostream>
#include <stdio.h>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int a,b;
        cin>>a>>b;
        int min_a,max_b;
        min_a=min(a,b);
        max_b=max(a,b);
        if((max_b-min_a)==1)
        {
            cout<<-1<<" "<<-1<<endl;
        }
        else if((max_b-min_a)==0)
        {
            if(a==1)
            {
                cout<<-1<<" "<<-1<<endl;
            }
            else
            {
                cout<<2<<" "<<a<<endl; 
            }
        }
        else
        {
            int cha=max_b-min_a;
            bool pan=false;
            for(int i=2;i*i<=cha;i++)
            {
                if(cha%i==0)
                {
                    cout<<i<<" ";
                    pan=true;
                    break;
                }
            }
            if(pan)
            {
                cout<<cha<<endl;
            }
            else
            {
                cout<<cha<<" "<<cha<<endl;
            }
        }
    }
    return 0;
}