macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

const MOD: usize = 998244353;

fn pow_mod(n: usize, k: usize, m: usize) -> usize {
    match k {
        0 => 1,
        _ if k % 2 == 0 => {
            let mut t = pow_mod(n, k / 2, m);
            (t * t) % m
        }
        _ => (pow_mod(n, k - 1, m) * n) % m,
    }
}




fn main(){
    input! {
        N: usize,
        M: usize,
    }
    let mut p_mod = vec![0;500005];
    for i in 0..M+1{
        p_mod[i] = pow_mod(i,N,MOD);
    }
    let mut ans = 0;
    for d in 1..M{
        let mut tmp = p_mod[d + 1] + 2*(MOD - p_mod[d]) + p_mod[d - 1];
        tmp %= MOD;
        tmp = (tmp * d) % MOD;
        tmp = (tmp * (M - d)) % MOD;
        ans += tmp;
        ans %= MOD;
    }
    let mut n = N;
    n %= MOD;
    ans *= n;
    ans %= MOD;
    ans *= M + 1;
    ans %= MOD;
    ans *= 499122177;
    ans %= MOD;
    println!("{}",ans);
}