#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int a, b;
    cin >> a >> b;
    if (a * 2 > b)
      cout << -1 << endl;
    else {
      cout << a << " " << a + a << endl;
    }
  }
}
