def main():
  import sys
  input = sys.stdin.readline

  N,M = map(int,input().split())
  A = tuple([int(input()) for _ in range(M)])
  
  dp = [0]*(N+1)
  dp[0] = 1
  if 1 in A:
    dp[1] = 0
  else:
    dp[1] = 1

  for i in range(2,N+1):
    if i not in A:
      dp[i] = (dp[i-1] + dp[i-2])%1000000007
    else:
      continue
  print(dp[N])

if __name__ == "__main__":
  main()