N, M = map(int, raw_input().split(" "))
A = {int(raw_input()) for _ in range(M)}

memo = [0] * (N + 1)
memo[0] = 1
memo[1] = 0 if 1 in A else 1

if N == 1:
    print(memo[1])
else:
    for i in range(2, N + 1):
        if i in A:
            continue
        memo[i] = (memo[i - 2] + memo[i - 1]) % 1000000007
    print(memo[N])
