N, M=map(int, input().split())
A=[int(input()) for _ in range(M)]
mod=10**9+7
step=[0]*(N+1)
step[1]=0 if 1 in A else 0
step[2]=0 if 2 in A else 1 if 1 in A else 0
for i in range(3, N+1):
  if i in A:
    continue
  step[i]=(step[i-1]+step[i-2])%mod
print(step[-1])