#include <bits/stdc++.h>
using namespace std;
#define LL long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
int n , c , a[N];
int sum;
int main()
{
	cin >> n >> c;
	for ( int i = 1 ; i <= n ; i++ )
	{
		cin >> a[i];
	}
	sort( a + 1 , a + n + 1 );
	for ( int i = 1 ; i <= n ; i++ )
	{
		sum += upper_bound( a + 1 , a + n + 1 , a[i] + c ) - lower_bound( a + 1 , a + n + 1 , a[i] + c );
	}
	cout << sum;
	return 0;
}

//菜鸟驿站
//老六专属