using System.Linq;
using System;

public class Hello
{
    static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var n = int.Parse(line[0]);
        var m = int.Parse(line[1]);
        line = Console.ReadLine().Trim().Split(' ');
        var a = Array.ConvertAll(line, long.Parse);
        getAns(n, m, a);
    }
    static void getAns(int n, int m, long[] a)
    {
        if (m % 2 == 1) { Console.WriteLine(0); return; }
        m /= 2;
        var hs = a.ToHashSet();
        var c = 0;
        foreach (var x in a) if (hs.Contains(x + m)) c++;
        var ans = c * (n - 2L);
        Console.WriteLine(ans);
    }
}