import java.util.Scanner;

public class Main {
    public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);

    	int x = sc.nextInt();
    	int y = sc.nextInt();
    	double l = sc.nextDouble();
    	int ans = (int)(Math.ceil(Math.abs(x) / l) + Math.ceil(Math.abs(y) / l));
    	int n = 0;
    	if(y < 0)n = 2;
    	if(y >= 0 && x != 0)n = 1;
    	System.out.println(ans + n);
    }
}