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