def main():
  N,M,*alst=map(int, open(0).read().split())
  mod=10**9+7
  dp = [0] * (N+1)
  dp[:2] = [1, 1 if 1 not in alst else 0]
  for i in range(2, N+1):
    if i not in alst:
      dp[i] = (dp[i-2] + dp[i-1])%mod
  print(dp[N])

main()