#include <bits/stdc++.h>
#define NMAX  10005
using namespace std;
int n , k;
int Male[NMAX] , Female[NMAX];

long long ans ;

void process()
{
        cin>> n >> k;
        for(int i = 1 ; i <= n ; i++)
        {
                int height;
                cin>>height;

                if(height > 0)  Male[height]++;

                if(height <= 0)  Female[-height]++;
        }

        for(int i = 1 ; i < NMAX ; i++)  Male[i] += Male[i-1];

        ans += 1ll * Female[0] * Male[k];

        for(int height = 1 ; height < NMAX - k ; height++)
        {
                ans += 1ll * Female[height] * (Male[height + k] - Male[height - 1]);
        }

        cout<<ans;
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr);
    cout.tie(nullptr);
    process();
    return 0;
}