import numpy as np

fft, ifft = np.fft.rfft, np.fft.irfft


def convolve(f, g):
    fft_len = 1
    while 2 * fft_len < len(f) + len(g) - 1:
        fft_len *= 2
    fft_len *= 2
    h = ifft(fft(f, fft_len, axis=0) @ fft(g, fft_len, axis=0), fft_len, axis=0)
    h = np.rint(h).astype(np.int64)
    return h[: len(f) + len(g) - 1]


def convolution(f, g, p=998244353):
    f1, f2 = np.divmod(f, 1 << 15)
    g1, g2 = np.divmod(g, 1 << 15)
    a, c = convolve(f1, g1) % p, convolve(f2, g2) % p
    b = (convolve(f1 + f2, g1 + g2) - a - c) % p
    return ((a << 30) + (b << 15) + c) % p


def poly_pow(f, n, p=998244353):
    res = np.eye(3, dtype=np.int64).reshape(1, 3, 3)
    while n:
        if n & 1:
            res = convolution(res, f, p)
        f = convolution(f, f, p)
        n >>= 1
    return res


def main():
    mod = 998244353
    P = np.array(
        [
            [[499122177, 0, 0], [332748118, 0, 0], [0, 0, 0]],
            [[0, 499122177, 0], [0, 332748118, 332748118], [0, 665496236, 332748118]],
        ]
    )
    v = np.array([[199648871, 0, 0], [0, 199648871, 598946612]])
    N, H = map(int, input().split())
    P = poly_pow(P, N - 1, mod)
    print(sum(np.sum(v[i] @ P[H - i :] % mod) for i in range(2)) % mod)


if __name__ == "__main__":
    main()