N,M=map(int,input().split())
B=[1]+[1]+[0]*(N-1)
for j in range(M):
    a=int(input())
    B[a]=-1
i=1
while i<=N:
    if B[i]==-1:
        B[i]=0
    else:
        B[i] = (B[i - 1] + B[i - 2]) % (10 ** 9 + 7)
    i+=1
print(B[N])