#include <bits/stdc++.h>
int main() {
  int n;
  scanf("%d", &n);
  for (int a = 1; a <= n; a++)
    for (int b = 1; b <= a; b++) {
      if (a % b == 0 && a * b > n && a / b < n) {
        printf("%d %d\n", a, b);
        return 0;
      }
    }
  printf("-1\n");
  return 0;
}
