#include <bits/stdc++.h>
using namespace std;
int main() {
  int w, h;
  cin >> w >> h;
  long long n;
  n = 4;
  int i;
  for (i = 1; i <= h + w - 2; i++) {
    n = n * 2;
    n = n % 998244353;
  }
  cout << n << endl;
  return 0;
}
