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

using ll = long long;
[[maybe_unused]] constexpr ll INF = (1LL << 60) - 1;

void solve() {
    ll n, d;
    cin >> n >> d;
    vector<ll> a(n);
    unordered_map<ll, ll> l, r;
    for (ll i = 0; i < n; ++i) {
        cin >> a[i];
        ++r[a[i]];
    }
    ll ans = 0;
    for (ll i = 0; i < n; ++i) {
        --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);
    ll t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}