const MOD: usize = 998244353;

fn power(base: usize, times: usize) -> usize {
    if times == 0 { return 1usize; }
    if times == 1 { return base; }
    let temp = power(base, times/2);
    temp * temp % MOD * power(base, times%2) % MOD
}

fn main() {
    let mut nm = String::new();
    std::io::stdin().read_line(&mut nm).ok();
    let nm: Vec<usize> = nm.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nm[0];
    let m = nm[1];

    let mut powers = vec![0usize; m+1];
    for i in 1..=m { powers[i] = power(i, n); }
    let mut result = 0usize;
    for i in 1..=m {
        result += (MOD + powers[i] - powers[i-1]) * i % MOD;
        result += MOD - (MOD + powers[m-i+1] - powers[m-i]) * i % MOD;
        result %= MOD;
    }
    let exp = (m+1) % MOD * power(2, MOD-2) % MOD * (n % MOD) % MOD;
    println!("{}", exp * result % MOD);
}