#include<iostream>
#include<algorithm>
using namespace std;
int main(){
    int n,m,a[1000001];
    cin>>n>>m;
    for (int i=0;i<n;i++) cin>>a[i];
    sort(a,a+n);
    long long cnt=0;
    int nowmax=0;
    for (int i=0;i<n-1;i++){
        if (a[n-1]-a[i]<m){break;}
        for (int j=nowmax;j<n;j++){
            if (a[j]-a[i]>=m){
                cnt+=n-j;
                nowmax=j;
                break;
            }
        }
    }
    cout<<cnt;
return 0;
}