#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, a, b = 0;
  cin >> x;
  for (int i = 1; i <= x; i++) {
    int k = 1;
    while (i * k <= x) {
      if (i * i * k > x && k < x) {
        a = i * k;
        b = i;
        break;
      } else
        k = k + 1;
    }
  }
  if (b == 0)
    cout << -1;
  else
    cout << a << " " << b;
  return 0;
}
