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