#include<bits/stdc++.h>
using namespace std;
#define YES cout<<"YES"<<endl;
#define NO cout<<"NO"<<endl;
const int N=2e5+5;
typedef vector<int> vi; 
#define pb push_back
typedef long long ll;
typedef long double ld; 
typedef vector<int>  vi;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
void solve()
{
    ll a,b;
    cin>>a>>b;
    ll c=abs(a-b);
    ll res1=c;
    ll res2=-2;

    if(a==b&&a>1){
        cout<<2<<" "<<a<<endl;
        return;
    }
    if(c<=1){
        cout<<-1<<" "<<-1<<endl;
        return;
    }
    for(int i=2;i<=(sqrt(c));i++){
        if(c%i==0){
            res2=i;
            break;
        }
    }
    if(res2==-2){
        cout<<res1<<" "<<res1<<endl;
        return;
    }
    else
        cout<<res2<<" "<<res1<<endl;
}
int main()
{
    int t;
    cin>>t;
    while(t--){
        solve();
    }
    return 0;
}