#include <iostream>
using namespace std;

#include <atcoder/modint>
using mint = atcoder::modint998244353;

int main() {
    cin.tie(nullptr), ios::sync_with_stdio(false);
    int N, M;
    cin >> N >> M;
    mint ret = N, den = 1;
    for (int i = 1; i <= N * 2 + 1; ++i) den = den * i;
    for (int i = M; i <= M + N * 2; ++i) ret = ret * i;
    cout << (ret / den).val() << '\n';
}