import java.util.Scanner;

public class Main {
    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) {
                x = Math.abs(x);
                y = Math.abs(y);
                count += (y / l);
                if(y%l > 0) count++;
                if(x != 0) {
                    count++;
                    count += (x / l);
                    if(x%l > 0) count++;
                }
                
            } else if(y < 0) {
                x = Math.abs(x);
                y = Math.abs(y);
                if(x != 0) { 
                    count++;
                    count += (x / l);
                    if(x%l > 0) count++;
                    count++;
                    count += (y / l);
                    if(y%l > 0) count++;
                }
            }
            System.out.println(count);
        }
    }
}