#include <bits/stdc++.h>
using namespace std;
int main() {
  int number;
  cin >> number;
  int auxs[2] = {1, 1};
  bool found = false;
  for (int i = 1; i <= number && !found; i++) {
    for (int j = 1; j <= number && !found; j++) {
      if (i % j == 0 && i / j < number && i * j > number) {
        cout << i << " " << j << endl;
        found = true;
      }
    }
  }
  if (!found) cout << "-1" << endl;
}
