using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Magatro
{
    static void Main()
    {
        int a, b, c;
        a = int.Parse(Console.ReadLine());
        b = int.Parse(Console.ReadLine());
        c = int.Parse(Console.ReadLine());
        int cnt = 0;
        cnt = b >= 0 ? a==0?0:1 : 2;
        b = Math.Abs(b);
        a = Math.Abs(a);
        cnt += a % c == 0 ? a / c : a / c + 1;
        cnt += b % c == 0 ? b / c : b / c + 1;
        Console.WriteLine(cnt);
    }
}