from collections import Counter
n, m = map(int, input().split())
a = Counter(map(int, input().split()))
if m % 2:
    print(0)
    exit()
m2 = m // 2
ans = 0
for k, v1 in a.items():
    if k <= m2:
        v2 = a.get(k + m2, 0)
        ans += v1 * v2 * (n - v1 - v2)
print(ans)