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>.
import math
import os
import random
import re
import sys

# Complete the aVeryBigSum function below.
def compare(ar,d):
    suma = 0    
    ar = sorted(ar)
    for i in range(len(ar)):
        for j in range(i+1,len(ar)):
            if ar[j] - ar[i] <= d:
                suma += 1
            else:
                break
    
    return suma*2

if __name__ == '__main__':
    
    ar_count = int(input())

    distant = int(input())

    ar = []
    for i in range(ar_count):
        ar.append(int(input()))


    result = compare(ar,distant)

    print(result)





