#include<atcoder/all>
using namespace std;

int main(){
    int n, m;
    cin >> n >> m;
    atcoder::modint998244353 ans = n, div = 1;
    for(int i = 0, n2 = n << 1, mn = m + n2; i <= n2 && ans.val(); i++){
        ans *= mn - i;
        div *= i + 1;
    }
    cout << (ans / div).val() << '\n';
}