using System;
using System.Globalization;
using System.Linq;

class Program
{
    public static void Main(string[] args)
    {
        int x = int.Parse(Console.ReadLine());
        int y = int.Parse(Console.ReadLine());
        int k = int.Parse(Console.ReadLine());

        int count = 0;

        if (x != 0)
        {
            count++;
        }
        if (y < 0)
        {
            count++;
        }
        if (x != 0)
        {
            count += Math.Abs(x)/k;
            if (Math.Abs(x)%k != 0)
            {
                count++;
            }
        }
        if (y != 0)
        {
            count += Math.Abs(y) / k;
            if (Math.Abs(y) % k != 0)
            {
                count++;
            }
        }
        Console.WriteLine(count.ToString(CultureInfo.InvariantCulture));
    }
}

class Program54
{

    public static void Main54(string[] args)
    {
        int n = int.Parse(Console.ReadLine());
        Tuple<int,int>[] valueAndThresholds = new Tuple<int, int>[n];
        for (int i = 0; i < n; i++)
        {
            var line = Console.ReadLine().Split(' ').Select(element => int.Parse(element)).ToArray();
            valueAndThresholds[i] = new Tuple<int, int>(line[0], line[1]);
        }

        Array.Sort(valueAndThresholds, (tuple, tuple1) => (tuple.Item2 + tuple.Item1).CompareTo(tuple1.Item2 + tuple1.Item1));
        var size = valueAndThresholds.Sum(element => element.Item1);

        var dp = new int[size + 1];
        for (int i = 0; i < dp.Length; i++)
        {
            dp[i] = int.MinValue;
        }
        dp[0] = 0;
        for (int index = 0; index < n; index++)
        {
            var current = valueAndThresholds[index];
            var threshold = current.Item2;
            var value = current.Item1;
            for (int j = 0; j < threshold; j++)
            {
                if (j + value < size + 1)
                {
                    if (dp[j] != int.MinValue)
                    {
                        dp[j + value] = Math.Max(dp[j + value], dp[j] + value);
                    }                    
                }
            }
        }
        int max = 0;
        for (int i = 0; i < dp.Length; i++)
        {
            max = Math.Max(max, dp[i]);
        }
        Console.WriteLine(max.ToString(CultureInfo.InvariantCulture));
    }
}