import bisect
mod = 10 ** 9 + 7
N, K = map(int, input().split())
A = sorted(map(int, input().split()))

ans = 1
used = 0

for _ in range(N // 2):
    R = A.pop()
    i = bisect.bisect_right(A, K - R)
    ans *= max(0, i - used)
    ans %= mod
    used += 1

print(ans)