#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
//using mint = modint1000000007;
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> T;
template<typename T>bool chmax(T& a, const T& b) { if (a < b) { a = b;return true; } else { return false; } }
template<typename T>bool chmin(T& a, const T& b) { if (a > b) { a = b;return true; } else { return false; } }
template<class... Args> void dbg(Args&&... args) { ((cout << args << ' '), ...);cout << '\n'; }

const int di[] = { -1,0,1,0 };
const int dj[] = { 0,-1,0,1 };
const long long INF = 6000000000000000000;
const int inf = 1001001001;


int main(void) {
    int n, d; cin >> n >> d;
    map<int, ll> mpl, mpr;
    vector<ll> a(n, 0);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    for (int i = 0; i < n; i++) {
        mpr[a[i]]++;
    }
    ll ans = 0;
    for (int i = 0; i < n; i++) {
        ans += mpl[a[i] - d] * mpr[a[i] + d];
        mpl[a[i]]++;
        mpr[a[i]]--;
    }
    cout << ans << "\n";
}