/* 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
{
	public static void main (String[] args) throws java.lang.Exception
	{
	   Scanner s=new Scanner(System.in);
	   int n=s.nextInt();
	   System.out.println(factorial(n));
	}
	public static int factorial(int n){
		if(n==1){
			return 1;
		}
 
		return n*factorial(n-1);
	}
}

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