#include <bits/stdc++.h>
using namespace std;
long long power(long long x, long long n) {
  long long res = 1;
  while (n) {
    if (n & 1) {
      res = (res * x);
    }
    n >>= 1;
    if (n != 0) {
      x = (x * x);
    }
  }
  return res;
}
long long powerMOD(long long x, long long n) {
  long long res = 1;
  while (n) {
    if (n & 1) {
      res = (res * x) % 1000000007;
    }
    n >>= 1;
    x = (x * x) % 1000000007;
  }
  return res;
}
bool mycompare(pair<long long, long long> &a, pair<long long, long long> &b) {
  if (a.first == b.first) {
    return a.second < b.second;
  }
  return a.first > b.first;
}
bool mycompare1(pair<int, int> &a, pair<int, int> &b) {
  return a.second < b.second;
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  srand(time(NULL));
  long long i, m, j, k, n, t, x, l, c, ans;
  cin >> t;
  for (int i = 0; i < t; i++) {
    cin >> l >> x;
    if ((l * 2) > x) {
      cout << -1 << " " << -1 << "\n";
      continue;
    }
    cout << l << " " << 2 * l << "\n";
  }
}
