e-olym 1148

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
int main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);cout.tie(0);

   test
   {

       ll a,c,d,e;
       cin>>a>>c;
       if(c%a==0) cout<<a<<" "<<c<<endl;
       else cout<<-1<<endl;

   }


   return 0;
}