import java.util.Scanner;
import java.math.BigInteger;
 
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
    	Scanner in = new Scanner(System.in);
    	int a = in.nextInt();
    	BigInteger [] f = new BigInteger[30000];
    	f[0] = BigInteger.valueOf(1);
    	for(int i = 1; i <= a; i++)
    	{
    	  f[i]=f[i-1].multiply(BigInteger.valueOf(i));
    	}
	    System.out.print(f[a]);
	}
}