import java.util.Scanner;

/**
   Computes n! = 1 x 2 x ... (n - 1) x n, given n.
   We assume n is greater than zero and less than 12.

   Input: n, the integer value for which n! is to be computed.
   Output: n! -- the factorial of n
*/
public class Factorial
{
   public static void main(String[] args)
   {
      // Read value for n
      Scanner in = new Scanner(System.in);
      int n = in.nextInt();
      if(n <= 0){System.out.println("1"); return;}
      System.out.println(factorial(n));
   }
   public static int factorial(int n)
   {
      if(n == 0){return 1;}
      return n * factorial(--n);
   }
}