n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]

fibo=[0]*(n+1)
fibo[0]=1
fibo[1]=1 if 1 not in a else 0
mod=10**9+7
for i in range(2,n+1):
  if i in a:
    continue
  fibo[i]=(fibo[i-2]+fibo[i-1])%mod

print(fibo[-1])