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.Scanner;
class Main{
	static Scanner sc=new Scanner(System.in);
	public static void main(String[] args) {
		while(sc.hasNext()){
			int n = sc.nextInt();
			System.out.println(answar(n));
		}

	}
	static long answar(int n){
		long ans=1;
		for(int i=1;i<=n;i++){
			ans *= i;
		}

		return ans;
	}
}