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.*;

class Main{
	public static void main(String[] args) throws IOException{
		BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
		String s;
		int i,n;
		long c=1;
		try {
				s=r.readLine();
				n = Integer.parseInt(s);
				for(i=1;i<=n;i++)c*=i;
				System.out.println(c);
		} catch (Exception err) {
			System.exit(0);
		}
	}
}