#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	int n, d;
	cin >> n >> d;
	vector<int> a(n);
	rep(i, 0, n) cin >> a[i];
	ll ans = 0;
	map<int, ll> mp, mp1;
	rep(i, 0, n) mp[a[i]]++;
	rep(i, 0, n) {
		mp[a[i]]--;
		ans += mp[a[i] + d] * mp1[a[i] - d];
		mp1[a[i]]++;
	}
	cout << ans << endl;
}