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