import java.math.BigInteger;

 import java.util.Scanner;

 public class sss {

     /**

      * @param args

      */

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         Scanner in=new Scanner(System.in);

         BigInteger sum=BigInteger.ONE;

         int n;

         n=in.nextInt();

         for(int i=1;i<=n;i++)

             sum=sum.multiply(BigInteger.valueOf(i));

         System.out.println(sum);

     }

 }