#include<stdio.h>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<math.h>
using namespace std;
long long a[1100][4],c;

long long gy(long long m)
{
    long long r;
    for(r=2;r<=sqrt(m);r++)
        if(m%r==0)break;
    if(r>sqrt(m))r=m;
    return r;
}
int main()
{
    int T;
    scanf("%d",&T);
    int i;
    for(i=0;i<T;i++)
    {
        scanf("%lld %lld",&a[i][0],&a[i][1]);
        if(a[i][0]>a[i][1])
            swap(a[i][0],a[i][1]);
    }
    for(i=0;i<T;i++)
    {
        c=a[i][1]-a[i][0];
        if(a[i][1]==1&&a[i][0]==1)
        {
            a[i][2]=-1;
            a[i][3]=-1;
        }
        else if(c==0)
        {
            a[i][3]=a[i][1];
            a[i][2]=2;
        }
        else if(c-1<=0)
        {
            a[i][2]=-1;
            a[i][3]=-1;
        }
        else if(a[i][1]%c==a[i][0]%c)
        {
            a[i][3]=c;
            a[i][2]=gy(c);
        }
        else
        {
            a[i][2]=-1;
            a[i][3]=-1;
        }
        printf("%lld %lld\n",a[i][2],a[i][3]);
    }
    return 0;
}