#include <atcoder/modint>
#include <bits/stdc++.h>

#define ll long long

using namespace std;
using namespace atcoder;

using mint = modint998244353;

vector<mint> facts(1, 1);
vector<mint> invFacts(1, 1);

mint comb(int n, int r) {
    return facts[n] * invFacts[r] * invFacts[n-r];
}

int main() {
    ll H, W;
    cin >> H >> W;

    if (H == 1 || W == 1) {
        cout << 1 << endl;
        return 0;
    }

    for (int i = 1; i < max(H-1, W); i++) {
        facts.push_back(i * facts[i-1]);
        invFacts.push_back(1 / facts[i]);
    }

    mint ans = 0;

    for (int i = 0; i < min(2*H-2, 2*W-1); i++) {
        int x = i / 2;
        int y = (i+1) / 2;
        mint pow = mint(2).pow((H-1)*(W-1) - i);

        ans += pow * comb(H-2, x) * comb(W-1, y);
    }

    cout << ans.val() << endl;
}