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

/* we expect no more than MAX data in the file */
#define MAX 1000

/* declare our variables */
int n, i,fact;
float data[MAX];
float ave, sigma;


int factorial(int N);

main ()
{
  scanf("%d", &n);
  fact=factorial(n);
  printf("%d\n", fact);

}


int factorial(int N){
 

  if(N<=1)
  return(1);
  else
    return(N*factorial(N-1));
}