#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1e5+6;
int n,m;


int main(){
    int t;
    cin>>t;
    while(t--){
        cin>>n>>m;
        if(n<m){
            int t=m;
            m=n;
            n=t;
        }
        if(n-m==1||(n<=2&&m<2)){
            cout<<"-1 -1"<<endl;
            continue;
        }
        if(m==n){
            cout<<2<<" "<<m<<endl;
            continue;
        }
        if((n%2==1&&m%2==1)||(n%2==0&&m%2==0))
        {
            cout<<2<<" ";
        }
        else{
            if(n%m==0&&m!=1){
                
                int k=m;;
                for(int i=2;i<=sqrt(k);i++){
                    if(k%i==0){
                        k=i;
                        break;
                    }
                }
                cout<<k<<" ";
            }
            else{
                
                int k=n-m;
                for(int i=2;i<=sqrt(k);i++){
                    if(k%i==0){
                        k=i;
                        break;
                    }
                }
                cout<<k<<" ";
            }
        }
        cout<<n-m<<endl;
       
    }
}