JaeHyeonKim19

import java.io.*;

public class Main {
	static int factorial(int n) {
		if (n <= 1) return 1;
		return n * factorial(n-1);
	}
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		System.out.println(factorial(n));
	}
}