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