N, K = gets.split.map(&:to_i)
A = gets.split.map(&:to_i).sort
MOD = 10 ** 9 + 7

upper = A.select { |a| a > K / 2 }.reverse
lower = A.select { |a| a <= K / 2 }

ans = 1
ls = lower.size

upper.each_with_index do |a, i|
  lim = K - a
  idx = lower.bsearch_index { |b| lim < b } || lower.size

  ans *= (idx - i)
  ans = 0 if ans < 0
  ans %= MOD
  ls -= 1
end

while ls > 0
  ans *= (ls - 1)
  ans %= MOD
  ls -= 2
end

puts ans