#include <bits/stdc++.h>
using namespace std;
long long w, h, a[1005][1005];
long long mod = 998244353;
int main() {
  ios_base::sync_with_stdio(0);
  cin >> w >> h;
  long long cur = 4;
  for (int i = (1); i <= (w); i++) {
    a[i][1] = cur;
    cur = (cur + cur) % mod;
  }
  cur = 4;
  for (int i = (1); i <= (h); i++) {
    a[1][i] = cur;
    cur = (cur + cur) % mod;
  }
  for (int i = (2); i <= (w); i++)
    for (int j = (2); j <= (h); j++)
      a[i][j] = (a[i - 1][j] + a[i][j - 1]) % mod;
  cout << a[w][h];
}
