#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int a, b;
  for (a = 1; a <= n; a++) {
    for (b = 1; b <= a; b++) {
      if (a * b > n && a * 1.0 / b < n && a % b == 0) {
        printf("%d %d", a, b);
        goto end;
      }
    }
  }
  printf("-1");
end:
  return 0;
}
