#include<bits/stdc++.h>
#define int long long
using namespace std;
const int maxn=1005; 
const int mode=1e9+7;
int read(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){
        if(ch=='-') f=-1;
        ch=getchar();
    }
    while(isdigit(ch)){
        x=x*10+ch-'0';
        ch=getchar();
    }
    return x*f; 
}
int t,n,m,a,b;
signed main(){
    t=read();
    while(t--){
        a=read(); b=read();
        int temp=abs(a-b);
        if(temp==1){
            cout<<-1<<' '<<-1<<"\n";
            continue;
        }
        else if(temp==0){
            if(a==1) cout<<-1<<' '<<-1<<"\n";
            else cout<<2<<' '<<a<<"\n";
            continue;
        }
        else if(temp<4){
            cout<<temp<<' '<<temp<<"\n";
            continue;
        }
        else{
            bool juge=false;
            for(int i=2;i*i<=temp;++i){
                if(temp%i==0){
                    cout<<i<<' ';
                    juge=true;
                    break;
                }
            }
            if(!juge) cout<<temp<<' ';
            cout<<temp<<"\n";
        }
    }
    return 0;
}