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