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