n, m = map(int,input().split())
dangerList = [int(input()) for i in range(m)]
answerList = [0] * (n+2)
answerList[0] = 1
nextDanger = dangerList.pop(0)
for i in range(n):
  if i == nextDanger:
    if len(dangerList) > 0:
    	nextDanger = dangerList.pop(0)
  else:
    answerList[i+1] = (answerList[i+1] + answerList[i]) % 1000000007
    answerList[i+2] = (answerList[i+2] + answerList[i]) % 1000000007
print(answerList[n])