b task

#include <iostream>
#include <cmath>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <cstdio>
#include <map>
#include <utility>
#include <queue>
#include <stack>
#include <deque>
#include <iomanip>
#include <fstream>

#define INF (1<<30)
#define F first
#define S second
#define pb push_back
#define mp make_pair
#define FOR(a,b) for(int i = a; i < b; i++)
#define FORR(a,b) for(int i = a; i >= b; i--)
#define FORJ(a,b) for(int j = a; j < b; j++)
#define FORRJ(a,b) for(int j = a; j >= b; j--)
#define FORN(n) for(int i = 0; i < n; i++)
#define FORJN(n) for(int j = 0; j < n; j++)
#define endl '\n'

#define TASKNAME "che"

typedef long long ll;
typedef long double ld;

using namespace std;

const int MAXN = 3e5;

int n,r,j;
int pred = 1;
ll ans = 0;
vector<int> a(MAXN+10);

int main(){
    // freopen(TASKNAME".in", "r", stdin);
    // freopen(TASKNAME".out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n >> r;
    FORN(n){
        cin >> a[i];
    }
    for (int i=0; i < n && a[i]+r<a[n-1]; i++){
        j=pred;
        while(a[i] + r >= a[j] && j < n)
            j++;
        pred=j;
        ans += n - pred;
    }
    cout << ans << endl;
    return 0;
}