#include<iostream>
#include<vector>
#include<algorithm>
#include<atcoder/convolution>
using namespace std;
using namespace atcoder;
using ll=long long;
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

const ll MOD=998244353;

const int MAX=5e5+10;
vector<ll>fac(MAX),finv(MAX),inv(MAX);

void set_fac(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for (int i=2;i<MAX;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 cmb(int n,int r){
    if (r<0||n<r)return 0;
    return fac[n]*(finv[r]*finv[n-r]%MOD)%MOD;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    set_fac();
    int h,w;
    cin>>h>>w;
    vector<ll>A(h+1),B(w+1);
    rep(i,h+1){
        if(2*i-h>=0)A[i]=finv[h-i]*finv[2*i-h]%MOD;
    }
    rep(i,w+1){
        if(2*i-w>=0)B[i]=finv[w-i]*finv[2*i-w]%MOD;
    }
    vector<ll>C=convolution<MOD>(A,B);
    ll ans=0;
    rep(i,h+w+1){
        ans+=fac[i]*C[i]%MOD;
        ans%=MOD;
    }
    cout<<ans<<"\n";
}