#include <queue>
#include <math.h>
#include <stack>
#include <stdio.h>
#include <iostream>
#include <vector>
#include <iomanip>
#include <string.h>
#include <algorithm>
using namespace std;
#define LL long long
const int N = 2e5 + 10;
const int INF = 0x3f3f3f3f;
int n;
int s;
int a[N];
int ans;
int main()
{
	cin >> n;
	cin >> s;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
	}
	sort(a + 1, a + n + 1);
	for (int i = 1; i <= n; i++)
	{
		ans += upper_bound(a + 1, a + n + 1, a[i] + s) - lower_bound(a + 1, a + n + 1, a[i] + s);
	}
	cout << ans;
	return 0;
}