taskFruits

import java.util.Scanner;

public class Task3 {
    public static void main(String[] args) {
        Scanner sc =new Scanner(System.in);
        int countBox=Integer.parseInt(sc.nextLine());
        int k=1;
        int smallestBox=1;
        smallestBox =k;
        int nextOne =k*(k+1);
        int countOrange=0;
        int countApple=0;

        for (int i=0;i<=countBox;i++){
            if(i%2==0){
                countOrange+=nextOne;
            }
            if(i%2!=0){
                countApple+=smallestBox;
            }

        }


        System.out.println(Math.abs(countOrange-countApple));
    }
}