#include<bits/stdc++.h>
using namespace std;
#define maxn 200010
#define ll long long
int a[maxn];
int n,s;
int main()
{
        scanf("%d%d",&n,&s);
        for(int i=1;i<=n;i++)scanf("%d",&a[i]);
        ll ans=0;
        for(int i=2,l=1,r=2;i<n;i++)
        {
                while(a[i]-a[l]>s)l++;
                while(r<=n && a[r]-a[i]<=s)r++;
                ans+=1ll*(l-1)*(n-r+1);
        }
        printf("%lld\n",ans);
        return 0;
}