#include <bits/stdc++.h>

using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)
template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

void solve() {
	int n, d;
	cin >> n >> d;
	vector<int> a(n);
	rep(i, 0, n) cin >> a[i];
	map<int, ll> l, r;
	rep(i, 0, n) r[a[i]]++;
	ll ans = 0;
	rep(i, 0, n) {
		r[a[i]]--;
		ans += l[a[i] - d] * r[a[i] + d];
		l[a[i]]++;
	}
	cout << ans << '\n';
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout << fixed << setprecision(15);
	int t = 1;
	// cin >> t;
	while (t--) solve();
}