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

        int num = sc.nextInt();

        long answer = 1;

        for(int i = 1; i <= num; i++){
            answer = answer * i;
        }

        System.out.println(answer);

    }
}