#include <iostream>
#include <vector>
using namespace std;


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

template <typename modint> struct acl_fac {
    std::vector<modint> facs, facinvs;
    acl_fac(int N) {
        assert(-1 <= N and N < modint::mod());
        facs.resize(N + 1, 1);
        for (int i = 1; i <= N; i++) facs[i] = facs[i - 1] * i;
        facinvs.assign(N + 1, facs.back().inv());
        for (int i = N; i > 0; i--) facinvs[i - 1] = facinvs[i] * i;
    }
    modint ncr(int n, int r) const {
        if (n < 0 or r < 0 or n < r) return 0;
        return facs[n] * facinvs[r] * facinvs[n - r];
    }
    modint operator[](int i) const { return facs[i]; }
    modint finv(int i) const { return facinvs[i]; }
};
acl_fac<mint> fac(1000000);


auto gen(int H) {
    vector<mint> ret(H + 1);
    for (int n = (H + 1) / 2; n <= H; ++n) {
        int n2 = H - n;
        ret.at(n) = fac.finv(n - n2) * fac.finv(n2);
    }
    return ret;
}

int main() {
    int H, W;
    cin >> H >> W;
    auto f = gen(H), g = gen(W);

    auto vec = atcoder::convolution(f, g);
    auto ret = vec.front();
    for (int i = 1; i < int(vec.size()); ++i) ret += vec.at(i) * fac[i];
    cout << ret.val() << endl;
}