def main():
  N,M = map(int,input().split())
  a = [int(input()) for i in range(M)]
  m = 10**9+7

  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]
      dp[i] %= m
  print(dp[-1])

if __name__ == '__main__':
  main()