Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.



Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Example

Input

5


Output

120
import java.util.*;

class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);

	int n = sc.nextInt();

	long factorial = n;
	for(int i=1; i<n; i++){
	    factorial = factorial*(n-i);
	}

	System.out.println(factorial);
    }
}