import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) 
	{
		// 入力値の読み込み
		Scanner sc = new Scanner(System.in);
		int  x = sc.nextInt();
		int  y = sc.nextInt();
		int  n = sc.nextInt();
		int count=0;
		
		if(y < 0){
			count = 2;
		}else{
			if(!(x ==0)){
				count = 1;
			}
		}
		int xa = x/n;
		if(x%n > 0){
			xa += 1;
		}
		
		int ya = y/n;
		if(y%n > 0){
			ya += 1;
		}
		
		System.out.println(count + xa + ya);
	}
}