n,m = map(int,input().split())
l = [int(input()) for _ in range(m)]
q = 10**9+7
memo = [0]*(n+1)
memo[0]=1
def a(x):
  if x in l :
    return 0
  elif x==1:
    memo[1]=1
    return 1
  else:
    if memo[x]!=0:
      return memo[x]
    else:
      memo[x] = a(x-1)+a(x-2)
      return (a(x-1)+a(x-2))
print(a(n)%q)