#include <bits/stdc++.h>
using namespace std;
int a[10005];
int main() {
freopen("xs.in", "r", stdin);
freopen("xs.out", "w", stdout);
long long n,m,cnt=0;
cin>>n>>m;
for(int i=1;i<=n;i++){
cin>>a[i];
}
sort(a+1,a+n+1);
for(int i=1;i<=n;i++){
int p=upper_bound(a+i+2,a+n+1,m+a[i])-a;
long long k=p-i-1;
cnt=cnt+k*(k-1)/2;
}
cout<<cnt;
return 0;
}