N,M=map(int,input().split())
mod=10**9+7
A=set([int(input()) for i in range(M)])

data=[0 for i in range(N)]
if 1 not in A:
    data[0]=1
if 2 not in A:
    data[1]=1+data[0]


for i in range(2,N):
    if i+1 not in A:
        data[i]=data[i-1]+data[i-2]
        data[i]%=mod

#print(data)

print(data[-1])
