li = list(map(int,input().split()))
n,m=li[0],li[1]
_list=[int(input()) for i in range(m)]
is_safe = [True] * (n+1)
for a in _list:
  is_safe[a] = False
DP=[1, 1] if is_safe[1] == True else [1, 0]
for i in range(n-1):
  if is_safe[i+2] == False:
    DP+= [0]
  else:
    DP += [DP[i] + DP[i+1]]
print(DP[n]%=1000000007 if DP[n] != 0 else 0)