#if 1
// clang-format off
#include <bits/stdc++.h>

#include <atcoder/all>

using namespace atcoder;
typedef modint998244353 mint93;
typedef modint1000000007 mint17;
typedef modint mint;

using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
using lf = long double;
using pll = pair<ll, ll>;
#define vec vector
template <class T> using v = vector<T>;
template <class T> using vv = v<v<T>>;
template <class T> using vvv = v<vv<T>>;
using vl = v<ll>;
using vvl = vv<ll>;
using vvvl = vvv<ll>;
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }

#define FOR(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
#define rep(i, N) for (ll i = 0; i < (ll)(N); i++)
#define rep1(i, N) for (ll i = 1; i <= (ll)(N); i++)
#define rrep(i, N) for (ll i = N - 1; i >= 0; i--)
#define rrep1(i, N) for (ll i = N; i > 0; i--)
#define fore(i, a) for (auto &i : a)
#define fs first
#define sc second
#define eb emplace_back
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define UNIQUE(x) (x).erase(unique((x).begin(), (x).end()), (x).end());
#define YES(x) cout << ((x) ? "YES\n" : "NO\n");
#define Yes(x) cout << ((x) ? "Yes\n" : "No\n");
#define yes(x) cout << ((x) ? "yes\n" : "no\n");
#define min(x, y) ((x) < (y) ? (x) : (y))
#define max(x, y) ((x) > (y) ? (x) : (y))
template <class T, class U> void chmin(T &t, const U &u) { if (t > u) t = u; }
template <class T, class U> void chmax(T &t, const U &u) { if (t < u) t = u; }
const int inf = (1 << 29);
const ll infl = (1LL << 60);
const ll mod93 = 998244353;
const ll mod17 = 1000000007;
int popcnt(uint x) { return __builtin_popcount(x); }
int popcnt(ull x) { return __builtin_popcountll(x); }
int bsr(uint x) { return 31 - __builtin_clz(x); }
int bsr(ull x) { return 63 - __builtin_clzll(x); }
int bsf(uint x) { return __builtin_ctz(x); }
int bsf(ull x) { return __builtin_ctzll(x); }

template <class T> istream &operator>>(istream &is, vector<T> &x) { for (auto &y : x) is >> y; return is; }
template <class T> ostream &operator<<(ostream &os, vector<T> &x) {
  for (unsigned int i = 0, size = x.size(); i < size; i++)
    os << x[i] << (i == size - 1 ? "" : " ");
  return os;
}
template <class T, class S> istream &operator>>(istream &is, pair<T, S> &x) { return is >> x.first >> x.second; }
template <class T, class S> ostream &operator<<(ostream &os, pair<T, S> &x) { return os << x.first << " " << x.second; }

ll rand_int(ll l, ll r) {  // [l, r]
  static random_device rd;
  static mt19937 gen(rd());
  return uniform_int_distribution<ll>(l, r)(gen);
}
template <long long MOD = 998244353> struct binomial {
  long long n;
  std::vector<atcoder::static_modint<MOD>> fact, ifact;
  binomial(long long n) : n(n), fact(n + 1), ifact(n + 1) {
    fact[0] = 1;
    for (int i = 1; i <= n; i++)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i > 0; i--)
      ifact[i - 1] = ifact[i] * i;
  }
  atcoder::static_modint<MOD> operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};
// clang-format on
#endif

// #define _GLIBCXX_DEBUG

void solve() {
  ll h, w;
  cin >> h >> w;
  v<mint93> a(h + 1), b(w + 1);
  // c1 + c2 = i
  // c1 + 2 * c2 = h
  binomial<mod93> comb(2 * (h + w));
  rep(i, h + 1) {
    ll c2 = h - i;
    ll c1 = h - 2 * c2;
    a[i] = comb(i, c1) * comb.ifact[i];
  }
  rep(i, w + 1) {
    ll c2 = w - i;
    ll c1 = w - 2 * c2;
    b[i] = comb(i, c1) * comb.ifact[i];
  }
  v<mint93> c = convolution(a, b);
  // cout << h << " " << w << " " << c.size() << endl;
  mint93 ans = 0;
  rep(i, c.size()) {
    ans += c[i] * comb.fact[i];
  }
  cout << ans.val() << "\n";
}

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);

  ll t = 1;
  // cin >> t;
  while (t--)
    solve();
}