def main():

    div = 1000000007

    n, m = map(int, input().split())
    a = [int(input()) for i in range(m)]

    f = [0] * (n + 1)
    f[0] = 1

    if 1 not in a:
        f[1] = 1

    for i in range(2, n + 1):
        if i in a:
            continue
        f[i] = (f[i - 1] + f[i - 2]) % div

    print(f[-1])


if __name__ == '__main__':
    main()
