import java.util.Scanner;
import java.io.BufferedInputStream;
import java.math.*;

 class Main{

	public static void main(String[] args)throws Exception {
		Scanner s = new Scanner(new BufferedInputStream(System.in));
		int a=s.nextInt();
		BigInteger bi = BigInteger.valueOf(a*(a-1)*(a-2)*(a-3)/4/3/2/1);
		System.out.println(bi);
 	}
}