#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <ctime>

using namespace std;

template <typename T>
T gcd(T a, T b) {
    while (a && b) {
        a %= b;
        swap(a, b);
    }
    return a + b;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    long long r;
    cin >> n >> r;
    vector<long long> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }

    int first = 0;
    int second = 0;

    while (a[second] - a[first] <= r) {
        second++;
        if (second == n) {
            break;
        }
    }

    long long ans = 0;
    while (second < n) {
        ans += n - second;
        first++;
        while (a[second] - a[first] <= r) {
            second++;
            if (second == n) {
                break;
            }
        }
    }

    while (a[second] - a[first] < r) {
        ans += n - second;
        first++;
        if (first == n) {
            break;
        }
    }

    cout << ans;

    return 0;
}