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 stdIn = new Scanner(System.in);
		int n = stdIn.nextInt();
		long ans = 1;
		for(int i = 1; i <= n; ++i)
		{
			ans *= i;
		}
		System.out.println(ans);
	}
}