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 sys


def solution(n, d, a_arr):

    count = 0
    for i in range(len(a_arr)):
        for j in range(len(a_arr)):
            if i == j:
                continue
            diff = abs(a_arr[i]-a_arr[j])
            #print(diff, d, count)
            if diff <= d:
                count += 1

    return count


if __name__ == '__main__':
    n = sys.stdin.readline()

    while n:
        n_in, d = n.split()  # array length
        a_arr = [int(i) for i in sys.stdin.readline().split()]  # input array
        print(solution(int(n_in), int(d), a_arr))
        n = sys.stdin.readline()
