항저우 전보 1042 N!

import java.io.*;

import java.util.*;

import java.math.*;

public class Main {

       public static void main(String args[])

       {

    	   Scanner cin=new Scanner(System.in);

    	   int n;

    	   BigInteger s;

    	   while(cin.hasNextInt())

    	   {

    		   s=BigInteger.valueOf(1);

    		   n=cin.nextInt();

    		   for(int i=2;i<=n;i++)

    		   {

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

    		   }

    		   System.out.println(s);

    	   }

       }

}