def main():
	n = int(input())
	k = int(input())
	arr = [int(input()) for _ in range(n)]
	count = 0
	mp = {}
	for i in range(n):
		comp = k+arr[i]
		if comp in mp:
			count+=mp[comp]
		if arr[i] in mp:
			mp[arr[i]]+=1
		else:
			mp[arr[i]]=1
	print(count)
	return 
	
	
if __name__=="__main__":
	main()