According to the regulations of Berland's army, a reconnaissance unit should consist of exactly two soldiers. Since these two soldiers shouldn't differ much, their heights can differ by at most *d* centimeters. Captain Bob has *n* soldiers in his detachment. Their heights are *a*<sub class="lower-index">1</sub>, *a*<sub class="lower-index">2</sub>, ..., *a*<sub class="lower-index">*n*</sub> centimeters. Some soldiers are of the same height. Bob wants to know, how many ways exist to form a reconnaissance unit of two soldiers from his detachment.

Ways (1, 2) and (2, 1) should be regarded as different.
The first line contains two integers *n* and *d* (1 ≤ *n* ≤ 1000, 1 ≤ *d* ≤ 10<sup class="upper-index">9</sup>) — amount of soldiers in Bob's detachment and the maximum allowed height difference respectively. The second line contains *n* space-separated integers — heights of all the soldiers in Bob's detachment. These numbers don't exceed 10<sup class="upper-index">9</sup>.
# -*- coding: utf-8 -*-
"""
Created on Sun Sep 26 20:55:06 2021

@author: cheehong
"""

l=list(map(int, input().split()))
n=l[0]
h=l[1]
s=list(map(int, input().split()))
k=0
t=0
while k<n:
    r=0
    while r<n:
        if r!=k:
            if s[k]>s[r]:
                if int(s[k])-int(s[r])<=h:
                    t+=1
            else:
                if int(s[r])-int(s[k])<=h:
                    t+=1
        r+=1
    k+=1
print(t)