N,M = map(int,input().split())
if M % 2 == 1:
    print(0)
    exit()
M2 = M // 2
N2 = N - 2
A = list(map(int,input().split()))
S = set(A)
ans = 0
cnt = 0
for a in A:
    if a + M2 in S:
        cnt += 1
print(cnt * N2)