import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		int x = sc.nextInt(); int y = sc.nextInt(); int L = sc.nextInt();
		
		int ans = 0;
		
		if (y>=0 && x!=0) ans += 1;
		else if (y<0 && x!=0) ans += 2;
		
//		System.out.println(":"+ans);
		
		if (x%L == 0) ans += Math.abs(x/L);
		else ans += Math.abs(x/L) + 1;
		
//		System.out.println(":"+ans);
		
		if (y%L == 0) ans += Math.abs(y/L);
		else ans += Math.abs(y/L) + 1;
		
		System.out.println(ans);
		
	}
}