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