#include <bits/stdc++.h>
using namespace std;
ostream &operator<<(ostream &out, string str) {
  for (char c : str) out << c;
  return out;
}
template <class L, class R>
ostream &operator<<(ostream &out, pair<L, R> p) {
  return out << "(" << p.first << ", " << p.second << ")";
}
template <class T>
auto operator<<(ostream &out, T &&x) -> decltype(x.begin(), out) {
  out << '{';
  for (auto &e : x) out << e << (&e == &*--x.end() ? "" : ", ");
  return out << '}';
}
template <class... Args>
void dump(Args &&...args) {
  ((cerr << args << ";  "), ...);
}
template <class T>
int size(T &&a) {
  return (int)a.size();
}
using LL = long long;
using PII = pair<int, int>;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int t;
  cin >> t;
  for (int _t = 0; _t < t; _t++) {
    int l, r;
    cin >> l >> r;
    if (2 * l > r)
      cout << "-1 -1\n";
    else
      cout << l << " " << 2 * l << "\n";
  }
}
