import java.util.Scanner;

public class Robot2 {

    public static void main(String[] args) {
        
        Scanner scanner = new Scanner(System.in);
        
        double x = scanner.nextInt();
        double y = scanner.nextInt();
        double l = scanner.nextInt();
        
        double count = 0;
        
        //回転
        if(y<0){
            count++;
        }
        
        if(x != 0){
            count++;
        }
        
        x = Math.abs(x);
        y = Math.abs(y);
        
        //進む回数 -> 距離　/ L (切り上げ)
        count += Math.ceil(x/l) + Math.ceil(y/l);
        
        System.out.println((int)count);
        
    }
    
}