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 comb(n: usize, r: usize) -> usize {
    let mut ret = 1usize;
    for i in 1..=r {
        ret *= n+1-i;
        ret %= MOD;
        ret *= power(i, MOD-2);
        ret %= MOD;
    }
    ret
}

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

    println!("{}", comb(a+b-2, a-1));
}