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.io.*;
import java.util.*;
public class Main {public static void main(String[] args) {Scanner sc = new Scanner(new BufferedReader(new InputStreamReader(System.in)));int n=sc.nextInt();long p=1;for(int i=1;i<=n;i++)p*=i;System.out.println(p);}}