#include <bits/stdc++.h>
using namespace std;
int main() {
  int x;
  int a, b;
  cin >> x;
  for (a = 1; a <= x; a++) {
    for (b = 1; b <= x; b++) {
      if (a % b == 0 && a * b > x && a / b < x) {
        cout << a << " " << b;
        return 0;
      }
    }
  }
  cout << -1;
  return 0;
}
