#include <bits/stdc++.h>
#define mx 200010
using namespace std;
typedef long long ll;
ll A[mx];
int main(){
	ll n,m;
	cin>>n>>m;
	for(int i=0;i<n;i++)
		cin>>A[i];
    sort(A,A+n);
    ll ans=0;
    for(int i=0,l=0,r=0;i<n;i++)
    {
    	while(l<n&&A[l]<A[i]+m)
    		l++;
		while(r<n&&A[r]<=A[i]+m)
			r++;
		ans+=r-l;
	}
	cout<<ans;
	return 0;
}