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

namespace ConsoleApp1
{
    internal class Program
    {
        static void Main(string[] args)
        {
            List<int> numbers = Console.ReadLine().Split(", ").Select(int.Parse).ToList();
            int k = int.Parse(Console.ReadLine());

            Console.WriteLine(FindCount(numbers, k));
        }

        public static int FindCount(List<int> numbers, int k)
        {
            int result = 0;

            List<List<int>> array = new List<List<int>>();

            for (int i = 0; i < numbers.Count - 1; i++)
            {
                for (int j = i + 1; j < numbers.Count; j++)
                {
                    if (numbers[i] + k == numbers[j])
                    {
                        result++;
                        array.Add(new List<int>(new int[] { numbers[i], numbers[j] }));
                    }
                }
            }
            var distinct = array.GroupBy(x => string.Join(",", x), (y, newArray) => newArray.First());

            return distinct.Count();
        }
    }
}