/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	static int f(int i){
		if(i==0)
			return 1;
		else
			return i * f(i-1);
	}

	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println(f(6));
	}
}