#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<vector>
using namespace std;
typedef long long LL;
const int N=100005;
int T;
int solve (int x)
{
    for (int u=2;u*u<=x;u++)
    if (x%u==0) return u;
    return x;
}
int main()
{
    scanf("%d",&T);
    while (T--)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        if (a<b) swap(a,b);
        int n=a-b;
        if (n==1) printf("-1 -1\n");
        else if (n==0)
        {
            if (a==1) printf("-1 -1\n");
            else printf("2 %d\n",a);
        }
        else printf("%d %d\n",solve(n),n);
    }
    return 0;
}