#include <bits/stdc++.h>
#include <atcoder/convolution>
using namespace std;
const long long MOD = 998244353;
int main(){
  int H, W;
  cin >> H >> W;
  vector<long long> inv(H + W + 1);
  inv[1] = 1;
  for (int i = 2; i <= H + W; i++){
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
  }
  vector<long long> fact(H + W + 1), finv(H + W + 1);
  fact[0] = 1;
  finv[0] = 1;
  for (int i = 1; i <= H + W; i++){
    fact[i] = fact[i - 1] * i % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
  vector<long long> f1(H + 1), f2(W + 1);
  for (int i = 0; i <= H; i++){
    if (H <= i * 2 && i <= H){
      f1[i] = finv[H - i] * finv[i * 2 - H] % MOD;
    }
  }
  for (int i = 0; i <= W; i++){
    if (W <= i * 2 && i <= W){
      f2[i] = finv[W - i] * finv[i * 2 - W] % MOD;
    }
  }
  vector<long long> g = atcoder::convolution(f1, f2);
  long long ans = 0;
  for (int i = 0; i <= H + W; i++){
    ans += g[i] * fact[i] % MOD;
  }
  ans %= MOD;
  cout << ans << endl;
}