#include <stdio.h>
#include <stdlib.h>

int facto(int n) {
  if(n<2)
    return 1;
  return facto(n-1)*n;
}

int main(int argc, char** argv) {
  int n;
  printf("n = ?\n");
  scanf("%d", &n);

  printf("%d! = %d\n", n, facto(n));
  return EXIT_SUCCESS;
}