import java.util.Scanner;

public class Main2 {
    public static void main(String[] args) {
        try (Scanner scan = new Scanner(System.in)) {
            int x = Integer.parseInt(scan.next());
            int y = Integer.parseInt(scan.next());
            int l = Integer.parseInt(scan.next());
            int count = 0;
            
            if(y < 0) count+=2;
            else if(y >= 0 && x != 0) count++;              
              
            count += (Math.abs(y)/l) + (Math.abs(y)%l>0? 1:0);
            count += (Math.abs(x)/l) + (Math.abs(x)%l>0? 1:0);
            
            System.out.println(count);
         }
    }
}