#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    long long l, r;
    cin >> l >> r;
    if (2 * l <= r) {
      cout << l << " " << 2 * l << '\n';
    } else
      cout << -1 << " " << -1 << '\n';
  }
  return 0;
}
