#include <bits/stdc++.h>
using namespace std;
#include <atcoder/modint>
using namespace atcoder;
using mint = modint998244353;
using ll = long long;
#define fix(x) fixed << setprecision(x)
#define rep(i, n) for(int i = 0; i < n; ++i)
#define all(x) (x).begin(),(x).end()
template<class T>bool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool chmax(T&a, const T&b){if(a<b){a=b;return 1;}return 0;}
constexpr ll INFLL = (1LL << 62), MOD = 998244353;
constexpr int INF = (1 << 30);

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll h,w;
    cin >> h >> w;
    cout << (mint(2).pow((h-2)*(w-2)+(h-2)+(w-2)+3)).val() << '\n';
    return 0;
}