#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)



// a^i mod M
template<u64 MOD>
u64 powm(u64 a,u64 i) {
  if(i == 0) return 1;
  u64 r = powm<MOD>(a*a%MOD,i/2);
  if(i&1) r = r*a%MOD;
  return r;
}
 

template<u64 MOD, u64 g>
void NTT(vector<u64>& A){
  int N=1;
  while(N < A.size()) N *= 2;
  for(int i=0,j=0; j<N; j++){
    if(i<j) swap(A[i],A[j]);
    for(int k=N>>1; k>(i^=k); k>>=1);
  }
  for(int i=1; i<N; i<<=1){
    u64 q=powm<MOD>(g,(MOD-1)/i/2), qj=1;
    for(int j=0; j<i; j++){
      for(int k=j; k<N; k+=i*2){
        u64 l = A[k];
        u64 r = A[k+i] * qj % MOD;
        A[k] = l+r;
        if(A[k] >= MOD) A[k] -= MOD;
        A[k+i] = l+MOD-r;
        if(A[k+i] >= MOD) A[k+i] -= MOD;
      }
      qj = qj * q % MOD;
    }
  }
}


template<u64 MOD, u64 g>
vector<u64> convolution(const vector<u64>& A, const vector<u64>& B){
  int Z = 1; while(Z < A.size() + B.size()) Z *= 2;
  vector<u64> Ax(Z), Bx(Z);
  u64 iZ = powm<MOD>(Z, MOD-2);
  rep(i, A.size()) Ax[i] = A[i];
  rep(i, B.size()) Bx[i] = B[i];
  NTT<MOD,g>(Ax); NTT<MOD,g>(Bx);
  rep(i,Z) Ax[i] = Ax[i] * Bx[i] % MOD;
  NTT<MOD,g>(Ax);
  reverse(Ax.begin() + 1, Ax.end());
  rep(i,Z) Ax[i] = Ax[i] * iZ % MOD;
  Ax.resize(A.size() + B.size() - 1);
  return move(Ax);
}


template<u64 MOD, u64 g>
vector<u64> powsumFPS(const vector<u64>& A, int n){
  if(n == 0){ return {}; }
  if(n == 1){ return { 1 }; }
  int N = 1; while(N<n) N*=2;
  int hN = N/2;
  vector<u64> hInv = powsumFPS<MOD,g>(A,hN);
  vector<u64> tgA(N,0);
  for(int i=0; i<min(N,(int)A.size()); i++) tgA[i] = A[i];
  u64 ig = powm<MOD>(g,MOD-2);
  NTT<MOD,g>(tgA);
  vector<u64> htInv(N,0);
  for(int i=0; i<hN; i++) htInv[i] = hInv[i];
  NTT<MOD,g>(htInv);
  vector<u64> R(N);
  for(int i=0; i<N; i++) R[i] = tgA[i] * htInv[i] % MOD;
  NTT<MOD,g>(R); reverse(R.begin()+1, R.end());
  for(int i=0; i<hN; i++) R[i] = R[hN+i];
  for(int i=hN; i<N; i++) R[i] = 0;
  NTT<MOD,g>(R);
  u64 iNN = powm<MOD>((u64)N*N%MOD,MOD-2);
  for(int i=0; i<N; i++) R[i] = R[i] * htInv[i] % MOD * iNN % MOD;
  NTT<MOD,g>(R); reverse(R.begin()+1, R.end());
  hInv.resize(n,0);
  for(int i=hN; i<n; i++) hInv[i] = R[i-hN];
  return move(hInv);
}


template<u64 MOD, u64 g>
vector<u64> invFPS(const vector<u64>& A, int n){
  u64 iA0 = powm<MOD>(A[0],MOD-2);
  vector<u64> xA(min(n,(int)A.size()));
  for(int i=0; i<xA.size(); i++) xA[i] = (MOD - A[i]) * iA0 % MOD;
  xA[0] = 0;
  xA = powsumFPS<MOD,g>(xA,n);
  for(int i=0; i<xA.size(); i++) xA[i] = xA[i] * iA0 % MOD;
  return move(xA);
}


static vector<u64> InvMOD = {1,1};

template<u64 MOD, u64 g>
vector<u64> logFPS(const vector<u64>& A, int n){
  int z = A.size();
  for(int i=InvMOD.size(); i<=n; i++){
    InvMOD.push_back((MOD - MOD/i) * InvMOD[MOD%i] % MOD);
  }
  auto res = invFPS<MOD,g>(A, n);
  vector<u64> Abuf(z);
  rep(i,z-1) Abuf[i] = A[i+1] * (i+1) % MOD;
  res = convolution<MOD,g>(res, Abuf);
  res.resize(n);
  for(int i=n-2; i>=0; i--) res[i+1] = res[i] * InvMOD[i+1] % MOD;
  res[0] = 0;
  return res;
}


template<u64 MOD, u64 g>
vector<u64> expFPS(const vector<u64>& A, int n){
  vector<u64> res = {1};
  while(res.size() < n){
    int z = res.size();
    auto tmp = logFPS<MOD,g>(res,z*2);
    tmp[0] = MOD - 1;
    rep(i,min<int>(z*2,A.size())){
      tmp[i] = MOD - tmp[i] + A[i];
      if(tmp[i] >= MOD) tmp[i] -= MOD;
    }
    res = convolution<MOD,g>(res, tmp);
    res.resize(min(n,2*z));
  }
  return res;
}


template<u64 MOD, u64 g>
vector<u64> powFPS(const vector<u64>& A, u64 k){
  int n = A.size();
  int zerocnt = 0;
  rep(i,n) if(A[i] == 0) zerocnt = i+1; else break;
  if(zerocnt >= (n-1)/k+1) return vector<u64>(n,0);
  auto res = A;
  rep(i,n-zerocnt) res[i] = res[i+zerocnt];
  i64 A0 = res[0];
  i64 iA0 = powm<MOD>(A0,MOD-2);
  i64 pA0 = powm<MOD>(A0,k);
  rep(i,n) res[i] = res[i] * iA0 % MOD;
  res = logFPS<MOD,g>(res,n);
  rep(i,n) res[i] = res[i] * k % MOD;
  res = expFPS<MOD,g>(res,n);
  rep(i,n) res[i] = res[i] * pA0 % MOD;
  zerocnt *= k;
  res.resize(n);
  for(int i=n-1; i>=zerocnt; i--) res[i] = res[i-zerocnt];
  rep(i, zerocnt) res[i] = 0;
  return res;
}


const u64 MOD = 998244353;
const u64 g = 3;

int main(){
    u64 x,y; cin >> x >> y;
    if(x > y) swap(x,y);
    vector<u64> G = convolution<MOD,g>({1,2}, invFPS<MOD,g>({1,MOD-1}, x+1));
    G.resize(x+1);
    //for(auto g : G) cout << g << " "; cout << endl;
    
    auto B = powFPS<MOD,g>(G, y);
    rep(i,x) B[i+1] = (B[i+1] + B[i]) % MOD;
    //for(auto g : B) cout << g << " "; cout << endl;
    
    auto G2 = invFPS<MOD,g>(G, x+1);
    reverse(G2.begin(), G2.end());
    G2.push_back(0);
    reverse(G2.begin(), G2.end());

    B = convolution<MOD,g>(B, powsumFPS<MOD,g>(G2, x+1));
    u64 ans = B[x];
    cout << ans << endl;
    return 0;
}




struct ios_do_not_sync {
    ios_do_not_sync() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;