def main():
    mod = 1000000007
    N, M, *A = map(int, open(0).read().split())
    A = set(A)
    F = [0] * (N + 1)
    F[0] = 1
    if 1 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])
    print(F[N] % mod)


if __name__ == "__main__":
    main()
