N, M = map(int, input().split())
A = list(map(int, input().split()))
A.sort()
ans = 0
fl = 0
for a in A :
	while fl < N and A[fl] < a + (M // 2) :
		fl += 1
	if fl < N and A[fl] == a + (M // 2) :
		ans += 1
if M & 1 :
	ans = 0
print(ans * (N - 2))