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

using namespace std;
using namespace atcoder;

using mint = modint998244353;

mint comb(int n, int r, vector<mint> facts) {
    return facts[n] / (facts[r] * facts[n-r]);
}

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

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

    vector<mint> facts(max(H-1, W), 1);
    for (int i = 0; i < facts.size(); i++) {
        facts[i+1] = (i+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;
        ans += mint(2).pow((H-1)*(W-1) - i) * comb(H-2, x, facts) * comb(W-1, y, facts);
    }

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