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

typedef long long ll;

int main() {
    ll n, k;
    cin >> n >> k;

    vector<ll> a(n);

    for(ll i = 0; i < n; i++)
        cin >> a[i];

    sort(a.begin(), a.end());

    ll l = 0;
    ll ans = 0;

    for(ll r = 0; r < n; r++) {
        while(a[r] - a[l] > k)
            l++;

        ans += r - l;
    }

    cout << ans << '\n';

    return 0;
}