//11388 PROBLEM d: gcd lcm
#include

using namespace std;

int main()
{
int t;
unsigned int g, l;

cin >> t;
while (t--)
{
cin >> g >> l;
if ( g > l || l % g != 0)
cout << "-1" << endl;
else
cout << g << " " << l << endl;

}

//system ("pause");
return 0;
}