walkingstreet.cpp

#include<iostream>
#include<cstdlib>
#include<vector>
#include<algorithm>

#define long long long
#define nln '\n'

using namespace std;

int main()
{
    // Input
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0)->sync_with_stdio(0);
    //freopen("walkingstreet.inp", "r", stdin);
    long n, d;
    cin >> n >> d;
    vector<long> a(n);
    for (auto &i : a)
        cin >> i;
    // Process
    long ans = 0;
    for (const auto i : a){
        long pos = upper_bound(a.begin(), a.end(), i+d) - a.begin();
        if (pos == n)
            continue;
        ans += n-pos;
    }
    // Output
    cout << ans << nln;
    return 0;
}