#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long int n, i, m, mx = INT_MIN, mn = INT_MAX, k, c = 0, j, d = 0, t = 0,
                         sm = 0, pdt = 1;
  cin >> c;
  cin >> d;
  t = c + d;
  for (i = 1; i <= t; i++) {
    pdt *= 2;
    pdt %= 998244353;
  }
  cout << pdt << endl;
  return;
}
int main() {
  int t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
