#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second

mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
const ll MOD1000000007 = 1000000007;
const ll MOD998244353 = 998244353;
const ll MOD[3] = {999727999, 1070777777, 1000000007};
const ll LINF = 1LL << 60;
const int IINF = 1 << 30;

template<typename T> struct Edge{
    int to; T w;
    Edge(int to_, T w_=1){
        to = to_;
        w=w_;
    }
};
template<typename T> using Tree = vector<vector<Edge<T>>>;
template<typename T> using Graph = vector<vector<Edge<T>>>;
/* 容量&重み付きエッジ for Dinic */
template<typename T> struct REdge{
    int to;
    T cap;
    T cost;
    int rev;
    REdge(int to_, T cap_, T cost_=1){
        to = to_;
        cap = cap_;
        cost = cost_;
    }
    
    REdge(int to_, T cap_, T cost_, int rev_){
        to = to_;
        cap = cap_;
        cost = cost_;
        rev = rev_;
    }
};

/* 残余グラフ for Dinic */
template<typename T> using RGraph = vector<vector<REdge<T>>>;

using mint = modint998244353;

const ll MAX = 510000;
mint fac[MAX], finv[MAX], inv[MAX];
 
void cominit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(ll i=2; i<MAX; i++){
        fac[i] = fac[i-1] * i;
        inv[i] = mint(i).inv();
        finv[i] = finv[i-1] * inv[i];
    }
}
 
mint com(ll n, ll k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return mint(0);
    return fac[n] * finv[k] * finv[n-k];
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    cominit();
    ll h, w; cin >> h >> w;
    h++; w++;
    //dp_h[i]:=合計i個の矢印でh-1に到達する組み合わせ
    //dp_w[i]:=合計i個の矢印でw-1に到達する組み合わせ
    vector<mint> dp_h(h, 0), dp_w(w, 0);
    for(ll n2=0; n2<=(h-1)/2; n2++){
        ll n1 = (h-1)-n2*2;
        dp_h[n1+n2] = com(n1+n2, n1)*finv[n1+n2];
    }
    for(ll n2=0; n2<=(w-1)/2; n2++){
        ll n1 = (w-1)-n2*2;
        dp_w[n1+n2] = com(n1+n2, n1)*finv[n1+n2];
    }

    vector<mint> a, b;
    for(ll i=h/2; i<=h-1; i++) a.pb(dp_h[i]);
    for(ll j=w/2; j<=w-1; j++) b.pb(dp_w[j]);

    vector<mint> c = convolution(a, b);
    mint ans = 0;
    for(ll i=h/2+w/2; i<=h+w-2; i++) ans += fac[i]*c[i-(h/2+w/2)];
    cout << ans.val() << endl;
}