import collections

mod = 998244353


def fft_inplace(a, w):
    n = len(a)
    m = n
    t = 1
    while m >= 2:
        mh = m >> 1
        for i in range(0, n, m):
            for s in range(mh):
                j, k = i+s, i+mh+s
                a[j], a[k] = (a[j]+a[k]) % mod, (a[j]-a[k])*w[s*t] % mod
        m = mh
        t *= 2


def ifft_inplace(a, w):
    n = len(a)
    m = 2
    t = -(n >> 1)
    while m <= n:
        mh = m >> 1
        for i in range(0, n, m):
            for s in range(mh):
                j, k = i+s, i+mh+s
                a[k] *= w[s*t]
                a[j], a[k] = (a[j]+a[k]) % mod, (a[j]-a[k]) % mod
        m <<= 1
        t //= 2
    n_inv = pow(n, mod-2, mod)
    for i in range(n):
        a[i] = a[i] * n_inv % mod


def normal_convolution(a, b):
    n = max(len(a) + len(b) - 1, 1)
    c = [0] * n
    for i in range(len(a)):
        for j in range(len(b)):
            c[i+j] += a[i] * b[j]

    for i in range(n):
        c[i] %= mod
    return c


def convolution(a, b):
    n2 = max(len(a) + len(b), 1)

    if len(a) * len(b) < 1 << 16:
        return normal_convolution(a, b)

    n = 1 << (n2-1).bit_length()
    a = a + [0] * (n-len(a))
    b = b + [0] * (n-len(b))

    w_root = pow(3, (mod-1)//n, mod)
    w = [1] * n
    for i in range(1, n):
        w[i] = w[i-1] * w_root % mod

    fft_inplace(a, w)
    fft_inplace(b, w)
    c = [i*j % mod for i, j in zip(a, b)]
    ifft_inplace(c, w)
    return c[:n2]


class Poly:
    def __init__(Self, coeffs):
        Self.coeffs = coeffs

    def __add__(Self, other):
        n = max(len(Self.coeffs), len(other.coeffs))
        result = [0] * n
        for idx, i in enumerate(Self.coeffs):
            result[idx] += i
        for idx, i in enumerate(other.coeffs):
            result[idx] += i
            result[idx] %= mod
        return Poly(result)

    def __mul__(Self, other):
        return Poly(convolution(Self.coeffs, other.coeffs))


class Fraction:
    def __init__(Self, num, den):
        Self.num = num
        Self.den = den

    def __add__(Self, other):
        return Fraction(Self.num * other.den + Self.den * other.num, Self.den * other.den)


n, s = map(int, input().split())
s_inv = pow(s, mod-2, mod)
p = [i * s_inv % mod for i in map(int, input().split())]

fractions = collections.deque(
    Fraction(Poly([0, i ** 2 % mod]), Poly([1, i])) for i in p
)

while len(fractions) > 1:
    fractions.append(fractions.popleft() + fractions.popleft())

ans = 0
factorial = 2
for i in range(1, n + 1):
    ans += fractions[0].num.coeffs[i] * factorial % mod
    factorial = factorial * (i + 2) % mod
    ans %= mod

print(ans)