N,M=map(int,input().split())
a=[]
for _ in [0]*M:
    a.append(int(input()))

stepsum=[1]   #k段目までの組み合わせ
if a[0]==1:   #1段目がNGなら
    stepsum.append(0)
else:
    stepsum.append(1)
    
for i in range(2,N+1):
    stepsum.append(((stepsum[i-1]+stepsum[i-2])*(not(i in a)))%1000000007)

ans=stepsum[N]%1000000007
print(ans)