n, m = map(int, input().split())
a = [int(input()) for i in range(m)]
if m > n // 2:
  print(0)
else:
  dp = [0] * (n+1)
  dp[0] = 1
  if 1 not in a:
    dp[1] = 1
  for i in range(2, n+1):
    if i not in a:
      dp[i] = dp[i-1] + dp[i-2]
  print(dp[-1]%(10 ** 9 + 7))