#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for(int (i) = 0; i<(n); i++)

int main(){
    int n, d;
    cin >> n >> d;
    vector<ll> a(n);
    rep(i,n) cin >> a[i];

    unordered_map<ll,ll> m1, m2;
    ll ans = 0;
    rep(i,n){
        m2[a[i]] += m1[a[i]-d];
        ans += m2[a[i]-d];
        m1[a[i]]++;
    }
    cout << ans << endl;

}