mod = 998244353

def mod_pow(x, n, mod):
    result = 1
    while n > 0:
        if n & 1:
            result = result * x % mod
        x = x * x % mod
        n >>= 1
    return result

def mod_inv(x, mod):
    return mod_pow(x, mod - 2, mod)

def cmb(n, r, mod):
    if n < r:
        return 0
    if r == 0:
        return 1
    numerator = denominator = 1
    for i in range(r):
        numerator = numerator * (n - i) % mod
        denominator = denominator * (i + 1) % mod
    return numerator * mod_inv(denominator, mod) % mod

def count_ways(N, M, mod):
    result = 0
    for i in range(N - M + 1):
        result += cmb(N, M + i, mod)
        result %= mod
    return result

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

print(count_ways(N, M, mod))