#include <bits/stdc++.h>
using namespace std;
#if __has_include("all.hpp")
#include "all.hpp"
#else
#include <atcoder/all>
#endif
using namespace atcoder;
using mint=modint998244353;
int main(void){
    int n,m;
    cin>>n>>m;
    mint p2=2;
    cout<<p2.pow(n+m-2+(n-1)*(m-1)).val()<<endl;
    return 0;
}