#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

struct Fast
{
  Fast()
  {
    std::cin.tie(0);
    ios::sync_with_stdio(false);
  }
} fast;

#define rep(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rrep(i, a, b) for (int i = (int)(b)-1; i >= (a); i--)
#define ll long long

template <typename T>
bool chmax(T &a, const T &b)
{
  if (a < b)
  {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
bool chmin(T &a, const T &b)
{
  if (a > b)
  {
    a = b;
    return true;
  }
  return false;
}

using mint = modint998244353;

int main()
{
  int h, w;
  cin >> h >> w;

  int n = 4e5;
  vector<mint> fact(n + 1), ifact(n + 1);
  fact[0] = 1;
  rep(i, 0, n) fact[i + 1] = fact[i] * (i + 1);
  ifact[n] = fact[n].inv();
  rrep(i, 0, n) ifact[i] = ifact[i + 1] * (i + 1);

  vector<mint> f(h / 2 + 1, 0), g(w / 2 + 1, 0);
  rep(i, 0, h / 2 + 1) f[i] = ifact[i] * ifact[h - 2 * i];
  rep(i, 0, w / 2 + 1) g[i] = ifact[i] * ifact[w - 2 * i];

  auto a = convolution(f, g);
  mint ans = 0;
  rep(i, 0, a.size()) ans += a[i] * fact[h + w - i];
  cout << ans.val() << endl;
}