#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<vvvl> vvvvl;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
typedef vector<vvvb> vvvvb;
typedef pair<ll,ll> pl;
typedef pair<ll,pl> ppl;
typedef pair<ll,ppl> pppl;
typedef pair<ll,pppl> pppppl;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(a) begin(a),end(a)
#define sz(a) (int)(a).size()
#define F first
#define S second
#define bs(A,x) binary_search(all(A),x)
#define lb(A,x) (ll)(lower_bound(all(A),x)-A.begin())
#define ub(A,x) (ll)(upper_bound(all(A),x)-A.begin())
#define cou(A,x) (ll)upper_bound(all(A),x)-lower_bound(all(A),x))
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
//*
using mint=modint998244353;
const ll mod=998244353;
//*/
/*
using mint=modint1000000007;
const ll mod=1000000007;
//*/
//using mint=modint;
//*
typedef vector<mint> vm;
typedef vector<vm> vvm;
typedef vector<vvm> vvvm;
typedef vector<vvvm> vvvvm;
ostream&operator<<(ostream&os,mint a){os<<a.val();return os;}
istream&operator>>(istream&is,mint&a){int x;is>>x;a=mint(x);return is;}
//*/
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>p){os<<p.F<<" "<<p.S;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.F>>p.S;return is;}
template<typename T>ostream&operator<<(ostream&os,vector<T>v){rep(i,0,sz(v))os<<v[i]<<(i+1!=sz(v)?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
vm inv(const vm&f){
  vm g{1/f[0]};
  while(sz(g)<sz(f)){
    vm x(f.begin(),f.begin()+min(sz(f),2*sz(g)));
    x=convolution(x,convolution(g,g));
    g.resize(2*sz(g));
    rep(i,sz(g)/2,min(sz(x),sz(g)))g[i]-=x[i];
  }
  return {g.begin(),g.begin()+sz(f)};
}
int main(){
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
  
  ll N,K;cin>>N>>K;
  N+=K;
  vm a(2*K+2,1);
  rep(n,K+1,2*K+2)a[n]=a[n-1]-a[n-K-1]+pow_mod(2,n-K-1,mod);
  ll d=2*K+2;
  vm F(d+1);
  F[0]+=1;
  F[K]+=-2;
  F[K+1]+=1;
  F[2*K]+=2;
  F[2*K+1]+=-3;
  F[d]+=1;
  reverse(all(F));
  auto invF=inv(F);
  reverse(all(F));
  vvm G(40);
  G[0]=vm{0,1};
  auto rem=[&](vm&f){
  	if(sz(f)<=d)return;
  	reverse(all(f));
  	assert(f[0].val());
  	auto q=convolution(f,invF);
  	q.resize(sz(f)-sz(F)+1);
  	reverse(all(q));
  	q=convolution(q,F);
  	reverse(all(f));
  	f.resize(d);
  	rep(i,0,d)f[i]-=q[i];
  };
  vm ans={1},T={0,1};
  while(N){
  	if(N%2){ans=convolution(ans,T);rem(ans);}
  	T=convolution(T,T);rem(T);N/=2;
  }
  mint s=0;
  rep(i,0,d)s+=ans[i]*a[i];
  cout<<s<<endl;
  return 0;
}