//迷失
#include<iostream>
#include<cmath>
using namespace std;
int ifnum(int a)
{
    for(int i=2;i*i<=a;i++)
    {
        if(a%i==0)
        {
            return i;
        }
    }
    return a;
}
int findmaxc(int a,int b)
{
    int p=abs(a-b);
    if(p<=1)
    return -1;
    else
    return p;
}
int findminc(int a,int b)
{
    int p=abs(a-b);
    if(p<=1)
    return -1;
    else
    {
        return ifnum(p);
    }
}
int main()
{
    int T,a,b;
    cin>>T;
    for(int i=0;i<T;i++)
    {
        cin>>a>>b;
        if(a==b)
        {
            if(a==1&&b==1)
            {
                cout<<-1<<" "<<-1<<endl;
                continue;
            }
            cout<<2<<" "<<a<<endl;
            continue;
        }
        cout<<findminc(a,b)<<" "<<findmaxc(a,b)<<endl;
     } 
    return 0;
}