#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 / b < x) {
        cout << a << " " << b << endl;
        return 0;
      }
  puts("-1");
  return 0;
}
