package com.company;
    import java.util.Scanner;
    public class Codeforces592B {
    public static void main(String[] args) {
    Scanner input= new Scanner(System.in);
    int num1,num2;
    num1= input.nextInt();
    num2=(num1-2)*(num1-2);
    System.out.printf("%dn",num2);
    }//end of main
    }//end of codeforces592B