#include <iostream>
#include <vector>
#include <algorithm>
#include <map>

using namespace std;

int main()
{
  int n, d;
  cin >> n >> d;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];
  map<int, long long> mp1, mp2;
  long long ans = 0;
  for (int i = 0; i < n; ++i)
  {
    int pv = a[i] - d;
    if (mp2.find(pv) != mp2.end()) ans += mp2[pv];
    if (mp1.find(pv) != mp1.end()) mp2[a[i]] += mp1[pv];
    ++mp1[a[i]];
  }
  cout << ans << endl;
}