#include <bits/stdc++.h>

using namespace std;
using ll = long long;

/* p = 2^m a + 1
   mod          root
   998244353    3
   924844033    5
*/

const ll modc = 998244353, MAX=1000000;
const ll root = 3;
class mint {
    ll x;
public:
    mint(ll x=0) : x((x%modc+modc)%modc) {}
    mint operator-() const {
      return mint(-x);
    }
    mint& operator+=(const mint& a) {
        if ((x += a.x) >= modc) x -= modc;
        return *this;
    }
    mint& operator-=(const mint& a) {
        if ((x += modc-a.x) >= modc) x -= modc;
        return *this;
    }
    mint& operator*=(const  mint& a) {
        (x *= a.x) %= modc;
        return *this;
    }
    mint operator+(const mint& a) const {
        mint res(*this);
        return res+=a;
    }
    mint operator-(const mint& a) const {
        mint res(*this);
        return res-=a;
    }
    mint operator*(const mint& a) const {
        mint res(*this);
        return res*=a;
    }
    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t>>1);
        a *= a;
        if (t&1) a *= *this;
        return a;
    }
    mint inv() const {
        return pow(modc-2);
    }
    mint& operator/=(const mint& a) {
        return (*this) *= a.inv();
    }
    mint operator/(const mint& a) const {
        mint res(*this);
        return res/=a;
    }
    bool operator == (const mint& a) const{
        return x == a.x;
    }
    friend ostream& operator<<(ostream& os, const mint& m){
        os << m.x;
        return os;
    }
    friend istream& operator>>(istream& ip, mint &m) {
        ll t;
        ip >> t;
        m = mint(t);
        return ip;
    }
    ll val(){
        return x;
    }
};

vector<mint> ntt(vector<mint> a, bool inv = false){
    ll N = a.size(), m = 0, q = (modc-1)/N;
    // N=2^m, p=2^m q+1
    // g = r^q (DFT)
    // g = r^-q (IDFT)

    //p=2^m q+1
    //r^(p-1) = 1
    //r^(2^m q) = 1
    //(r^q) ^ (2^m) = 1
    //w_(2^m) = r^q
    //w_(2^(m-1)) = (r^q)^2
    //w_(2^(m-2)) = (r^q)^4
    
    for (int i=0; (1<<i)<N; i++) m++;
   
    for (int i=0; i<N; i++){
        int j=0;
        for (int k=0; k<m; k++) j |= (i>>k & 1) << (m-1-k);
        if (i < j) swap(a[i], a[j]);
    }

    mint g = (inv ? mint(root).pow(q).inv() : mint(root).pow(q));
    vector<mint> w(m+1);
    w[m] = g;
    for (int i=m-1; i>=1; i--) w[i] = w[i+1] * w[i+1];

    for (int b=1, i=1; b<N; b*=2, i++){
        for (int k=0; k<N; k += b*2){
            mint ww = 1;
            for (int j=0; j<b; j++){
                mint s = a[j+k], t = a[j+k+b] * ww;
                a[j+k] = s + t;
                a[j+k+b] = s - t;
                ww *= w[i];
            }
        }
    }
    
    if (inv){
        mint Ninv = mint(N).inv();
        for (int i=0; i<N; i++) a[i] *= Ninv;
    }
    return a;
}

//convolution c[k] = sum(i=0, k) a[i]b[k-i]
vector<mint> convolution(vector<mint> a, vector<mint> b){
    int s = a.size() + b.size() - 1;
    int t = 1;
    while(t < s) t *= 2;
    a.resize(t); b.resize(t);
    vector<mint> A = ntt(a); //DFT
    vector<mint> B = ntt(b); //DFT

    for (int i=0; i<t; i++) A[i] *= B[i];
    A = ntt(A, true); //IDFT
    
    return A;
}

vector<mint> f, finv;

mint inv(mint x){
    mint ans = 1;
    ll e = modc-2;

    while (e > 0){
        if ((e & 1LL)) ans *= x;
        e = e >> 1LL;
        x *= x;
    }

    return ans;
}

void init(){
    f.resize(MAX+1); finv.resize(MAX+1);
    f[0] = 1;
    for (int i=1; i<=MAX; i++) f[i] = f[i-1]*i;
    finv[MAX] = inv(f[MAX]);
    for (int i=MAX-1; i>=0; i--) finv[i] = finv[i+1] * (i+1);
}

int main(){

    init();
    int H, W;
    mint ans=0;
    cin >> H >> W;
    vector<mint> B(H+1), D(W+1);
    for (int b=0; b<=H/2; b++) B[H-b] = finv[H-b*2] * finv[b];
    for (int d=0; d<=W/2; d++) D[W-d] = finv[W-d*2] * finv[d];
    vector<mint> C = convolution(B, D);
    
    for (int i=0; i<=H+W; i++){
        ans += f[i] * C[i];
    }

    cout << ans << endl;

    return 0;
}