using System;
using System.Collections.Generic;
using System.Linq;

namespace FashionBoutique
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] quantityOfClothes = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int capacityOfRack = int.Parse(Console.ReadLine());

            Stack<int> clothesStack = new Stack<int>(quantityOfClothes);

            int countRack = 1;
            int sumClothes = 0;

            //if (clothesStack.Sum() == 0 || capacityOfRack == 0)
            //{
            //    countRack = 0;
            //    Console.WriteLine(countRack);
            //    return;
            //}

            while (clothesStack.Count > 0)
            {
                if (sumClothes < capacityOfRack)
                {
                    sumClothes += clothesStack.Pop();
                }
                else
                {
                    sumClothes -= capacityOfRack;
                    countRack++;
                }
            }

            if (sumClothes > 0 && countRack > 1)
            {
                countRack++;
            }

            Console.WriteLine(countRack);
        }
    }
}