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>.
#!/usr/bin/env python

import math
import sys
import itertools
import fractions

if __name__ == '__main__':
    wtf = sys.stdin.read()
    wtf = wtf.strip().split('\n')
    n,d = map(int, wtf[0].split())
    A = list(map(int, wtf[1].split()))
    ans = 0
    for i in range(n):
        for j in range(n):
            if j != i and abs(A[i]-A[j]) <= d:
                    ans += 1
    print(ans)
