rt

#include <iostream>
#include <unordered_map>
using namespace std;

int main()
{
    int N, C;
    cin >> N >> C;
    unordered_map<int, int> count;
    for (int i = 0; i < N; i++)
    {
        int temp;
        cin >> temp;
        count[temp]++;
    }
    int ans = 0;
    for (auto it = count.begin(); it != count.end(); it++)
    {
        int num = it->first;
        if (count.find(num - C) != count.end())
        {
            ans += count[num - C] * it->second;
        }
    }
    cout << ans;
    return 0;
}