#include #include #include using namespace std; using namespace atcoder; using mint = modint998244353; #define rep(i,n) for (int i = 0; i < (n); ++i) #define Inf32 1000000005 #define Inf64 1000000000000000001LL int main(){ long long h,w; cin>>h>>w; mint ans = mint(2).pow((h-1)*(w-1)); ans *= 4; cout<