def main():
  import sys
  input = sys.stdin.readline
  n,m=map(int,input().split())
  mod=pow(10,9)+7
  ans=[1]*(n+1)
  for _ in [0]*m:
    ans[int(input())]=0
  ans[2]=ans[1]+1 if ans[2]!=0 else 0
  for i in range(3,n+1):
    if ans[i]>0:
      ans[i]=(ans[i-1]+ans[i-2])%mod
  print(ans[-1])
if __name__ == '__main__':
    main()