#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <iomanip>
#include <stack>
#include <queue>
#include <numeric>
#include <map>
#include <unordered_map>
#include <set>
#include <fstream>
#include <chrono>
#include <random>
#include <bitset>
#include <atcoder/all>
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) ((int)(x).size())
#define pb push_back
using ll = long long;
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
ll gcd(ll a, ll b) {return b?gcd(b,a%b):a;}
ll lcm(ll a, ll b) {return a/gcd(a,b)*b;}

const ll mod = 998244353;

vector<ll> fac(500000), finv(500000), inv(500000);
void initcom(){
  fac[0] = fac[1] = finv[0] = finv[1] = inv[1] = 1;
  for(int i=2; i<500000; i++){
    fac[i] = (fac[i-1]*i) % mod;
    inv[i] = mod - inv[mod%i] * (mod/i) % mod;
    finv[i] = finv[i-1] * inv[i] % mod;
  }
}
ll nCr(int n, int k){
  if(n<k) return 0;
  if(n<0 || k<0) return 0;
  return fac[n] * (finv[k] * finv[n-k] % mod) % mod;
}

int main(){
  int H,W; cin >> H >> W;
  initcom();
  vector<ll> A(H+1,0);
  vector<ll> B(W+1,0);
  for(int i=1;i<=H;i++){
    A[i] = nCr(i,2*i-H)*finv[i]%mod;
  }
  for(int i=1;i<=W;i++){
    B[i] = nCr(i,2*i-W)*finv[i]%mod;
  }
  auto C = atcoder::convolution(A,B);
  ll ans = 0;
  for(int i=1;i<sz(C);i++){
    ans += C[i]*fac[i]%mod;
  }
  cout << ans%mod << endl;
  return 0;
}