N = int(input())
M = int(input())

MOD = 998244353


def modinv(x):
    return pow(x, MOD-2, MOD)

# 二項係数の左側の数字の最大値を max_len　とする。nとかだと他の変数と被りそうなので。
# factori_table = [1, 1, 2, 6, 24, 120, ...] 要は factori_table[n] = n!
# 計算時間はO(max_len * log(MOD))


max_len = N

factori_table = [1] * (max_len + 1)
factori_inv_table = [1] * (max_len + 1)
for i in range(1, max_len + 1):
    factori_table[i] = factori_table[i-1] * (i) % MOD
    factori_inv_table[i] = modinv(factori_table[i])


def binomial_coefficients(n, k):
    # n! / (k! * (n-k)! )
    return factori_table[n] * factori_inv_table[k] * factori_inv_table[n-k]


ans = pow(2, N, MOD)

for m in range(M):
    if N >= m:
        ans -= binomial_coefficients(N, m)
    ans %= MOD
print(ans)