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

public class Solution {
    public static void main(String[] args) throws Exception {
        //напишите тут ваш код
    Scanner in = new Scanner(System.in);
    int a = in.nextInt();

    if (a>0)
        {a= a*2;  System.out.print (a); }

    if (a<0)
        {a++; System.out.print (a);}

    if (a==0)
        {System.out.print (a);}


    }

}