#include <bits/stdc++.h>
using namespace std;
int main () {
	int N, D;
	cin >> N >> D;
	using ll = long long;
	map<int, ll> mp1, mp2;
	std::vector<int> A(N);
	for (auto& a : A) {
		cin >> a;
		mp1[a] ++;
	}
	ll ans = 0;
	for (int i = N-1; i>= 0; i --) {
		ll a = A[i];
		mp1[a] --;
		ans += mp1[a-D] * mp2[a+D];
		mp2[a] ++;
	}
	cout << ans << endl;
}