#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9 + 10;
const int MOD = 998244353;
long long pw(long long base, long long exp);
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  cout << (4LL * pw(2LL, n - 1) * pw(2LL, m - 1)) % MOD;
  return 0;
}
long long pw(long long base, long long exp) {
  long long ret = 1;
  while (exp) {
    if (exp % 2) ret *= base, ret %= MOD;
    base *= base;
    base %= MOD;
    exp >>= 1;
  }
  return ret;
}
