#include<bits/stdc++.h>
using namespace std;
int n,c,a[200010],ans;
int main() 
{
	cin>>n>>c;
	for(int i=0;i<n;i++)cin>>a[i];
	sort(a,a+n);
	for(int i=0;i<n;i++)ans+=(upper_bound(a,a+n,a[i]+c)-a)-(lower_bound(a,a+n,a[i]+c)-a);
	cout<<ans;
	return 0; 
}