// #pragma GCC optimize ("Ofast")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target ("avx,avx2,fma")
#include <bits/stdc++.h>

using std::cin, std::cout, std::cerr;
using ll = long long;

const ll P = 998244353;
ll Pow(ll a, ll b) {
    ll r = 1;
    for(; b; b /= 2) {
        if(b & 1)
            r = r * a % P;
        a = a * a % P;
    }
    return r;
}

int main() {
    std::ios::sync_with_stdio(false);
    ll n, m; cin >> n >> m;
    ll ans = Pow(2, n * m - 1 - (n - 2) - (m - 2));
    cout << ans << '\n';
}