#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#define rep(i, n) for(i = 0; i < n; i++)
#define int long long
using namespace std;

int n, d;
int a[100000];

signed main() {
	int i;

	cin >> n >> d;
	rep(i, n) cin >> a[i];

	map<int, int> mp1, mp2;
	vector<int> cnt(n);

	rep(i, n) {
		cnt[i] = mp1[a[i] - d];
		mp1[a[i]]++;
	}

	int ans = 0;
	rep(i, n) {
		ans += mp2[a[i] - d];
		mp2[a[i]] += cnt[i];
	}

	cout << ans << endl;
	return 0;
}