#include <bits/stdc++.h>
using namespace std;

int main()
{
    int tc;
    cin>>tc;
    while(tc--)
    {
        int gcd, lcm;
        cin>>gcd>>lcm;
        if(lcm%gcd==0) cout<<gcd<<" "<<lcm<<endl;
        else cout<<-1<<endl;2
    }
    return 0;
}