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];

    if n == 1 {
        println!("0");
        return;
    }
    let nmod = n % MOD;
    let mut patterns = 0usize;
    let pows = (0..=m).map(|i| if i > 0 { power(i, n) } else { 0 }).collect::<Vec<_>>();
    for i in 1..=m {
        let maxpat = MOD + pows[i] - pows[i-1];
        let minpat = MOD + pows[m+1-i] - pows[m-i];
        patterns += maxpat * i % MOD;
        patterns += MOD - minpat * i % MOD;
        patterns %= MOD;
    }
    let exp = (1+m) * power(2, MOD-2) % MOD * nmod % MOD;
    println!("{}", patterns * exp % MOD);
}