#include<bits/stdc++.h>
#include<algorithm>
using namespace std;
const int N=200000;
long arr[N];
long n,c;
long ans;

int main ()
{
    cin>>n>>c;
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }
    sort(arr,arr+n);
    for(int i=0;i<n;i++)
    {
       //ʹarriA
       int j=arr[i]+c;
       int a1=lower_bound(arr+i,arr+n,j)-arr;
       int a2=upper_bound(arr+i,arr+n,j)-arr;
       ans+=upper_bound(arr+i,arr+n,j)-lower_bound(arr+i,arr+n,j);
        
    }
    cout<<ans<<endl;
    
    return 0;
}