#include <bits/stdc++.h>
using namespace std;
void speed() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
int main() {
  speed();
  int n;
  cin >> n;
  for (int i = 0; i <= n; i++) {
    for (int g = 1; g <= n; g++) {
      for (int k = 1; k <= n; k++) {
        if (g % k == 0 && g * k > n && g / k < n) {
          cout << g << " " << k << endl;
          return 0;
        }
      }
    }
  }
  cout << -1 << endl;
  return 0;
}
