N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
mod =  1000000007
ret = [0] * (N+1)
ret[0] = 1
for i in range(1,N+1):
    if i in a:
        continue
    elif i == 1:
        ret[1] = 1
    else:
        ret[i] = ret[i-2] + ret[i-1]

print(ret[len(ret)-1]%mod)
