/*
int      %o/%lo 8 %d/%i/%ld/%li 10 %x/%lx 16
longlong %lld
float    %f/%e
double   %lf/%le
char     %c
char[]   %s
'a'=97
'z'=122
'A'=65
'Z'=90
'0'=48
'9'=57
*/
#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <ctime>
#include <limits>
#include <assert.h>
#include <stdlib.h>
using namespace std;
#define LL long long
#define ull unsigned long long
const int N=1e5+10;
const int INF=0x3f3f3f3f;
const double pi=3.1416;
int n,c,a[N],ans;

int main(){
	cin>>n>>c;
	for(int i=1;i<=n;i++){
		cin>>a[i];
	}
	sort(a+1,a+n+1);
	for(int i=1;i<=n;i++){
		ans+=upper_bound(a+1,a+n+1,a[i]+c)-lower_bound(a+1,a+n+1,a[i]+c);
	}
	cout<<ans<<endl;
return 0;
}