def main():
    N, M = map(int, input().split(" "))
    mod = 1000000007
    A = []
    for _ in range(M):
        A.append(int(input()))
    F = [0] * (N + 1)
    F[0] = 1
    if 1 not in A:
        F[1] = 1
    for i in range(2, N + 1):
        if i not in A:
            F[i] = (F[i-1] + F[i-2]) % mod
    print(F[N])


if __name__ == "__main__":
    main()
