#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int c = 0;
  for (int i = 2; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (i % j == 0)
        if (i * j > n)
          if (i / j < n) {
            cout << i << " " << j;
            c = 1;
            break;
          }
    }
    if (c == 1) break;
  }
  if (c == 0) cout << -1;
}
