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
#Take two integers n and d
arr2=[]
arr1=[]
x=str(input(""))
arr2=x.split()
for z in range(0,2):
    z1=arr2[z]
    arr1.append(int(z1))
#Take n spaace seperated integers-heights
arr3=[]
arr4=[]
x=str(input(""))
arr3=x.split()
count=0
for z in range(0,arr1[0]):
    z1=arr3[z]
    arr4.append(int(z1))
for i in range(0,arr1[0]-1):
    for j in range(i+1,arr1[0]):
        if(abs(arr4[i]-arr4[j])<=arr1[1]):
            count+=1
print(2*count)


    	 		 	  	 			 	  					 	 		