#include <iostream>
#include <algorithm>
#include <set>
using namespace std;

int contar_pares(int diff, set<int> numeros){
    int cont = 0;
    for (auto num: numeros){
        if (numeros.find(num - diff) != numeros.end()){
            cont++;
        }
        if (numeros.find(num + diff) != numeros.end()){
            cont++;
        }
    }
    return cont / 2;
}

int main(){
    int n, k;
    cin >> n >> k;
    int tamanho = n;
    set<int> numeros;
    for(int i = 0; i < tamanho; i++){
        int num;
        cin >> num;
        numeros.insert(num);
    }
    cout << contar_pares(k, numeros) << endl;

    return 0;
}