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