#include #if __has_include() #include #endif using namespace std; #define done(...) return pp(__VA_ARGS__) #define RD(T,...) T __VA_ARGS__;lin(__VA_ARGS__) #define LL(...) RD(ll,__VA_ARGS__) #define fo(i,...) for(auto[i,i##stop,i##step]=for_range(0,__VA_ARGS__);i(1,__VA_ARGS__);i>=i##stop;i+=i##step) #define defpp templatevoid pp(const auto&...a){[[maybe_unused]]const char*c="";((o<(a...);} #define entry defpp void main();void main2();}int main(){my::io();my::main();}namespace my{ #define use_ml998244353 using ml=atcoder::modint998244353; namespace my{ auto&operator<<(ostream&o,const atcoder::modint998244353&x){return o<<(int)x.val();} void io(){cin.tie(nullptr)->sync_with_stdio(0);cout<concept modulary=requires(T t){t.mod();}; templateconstexpr auto for_range(T s,T a,T b,T c=1){return array{a-s,b,(1-s*2)*c};} void lin(auto&...a){(cin>>...>>a);} constexpr auto even(auto x){return~x&1;} templateusing pack_back_t=tuple_element_t>; } namespace my{ templatestruct vec; templatestruct hvec_helper{using type=vec::type>;}; templatestruct hvec_helper<0,T>{using type=T;}; templateusing hvec=hvec_helper::type; templatestruct vec:vector{ using vector::vector; ll size()const{return vector::size();} }; templaterequires(sizeof...(A)>=2)vec(const A&...a)->vec>>; } namespace my{ templateT fac(ll n){static vecv{1};if(ll m=v.size();m<=n){v.resize(n+1);fo(i,m,n+1)v[i]=v[i-1]*i;}return v[n];} templateT fac_inv(ll n){static vecv{1};if(ll m=v.size();m<=n){v.resize(n+1);v[n]=fac(n).inv();of(i,n,m)v[i]=v[i+1]*(i+1);}return v[n];} templateT comb(ll n,ll k){ if(n<0||k<0||n)return fac(n)*fac_inv(k)*fac_inv(n-k); else { } } } namespace my{entry void main(){ LL(N,K); if(N==1){ if(K==1)done(1); if(K==2)done(3); if(K==3)done(3); if(K==4)done(3); if(K==5)done(1); if(K==6)done(1); } N+=2; use_ml998244353 ml ans=0; // 恒等 ans+=comb(N*2,K); // 上下反転 if(even(K))ans+=comb(N,K/2); // 180度回転 if(even(K))ans+=comb(N,K/2); // 左右反転 if(even(N)){ if(even(K))ans+=comb(N,K/2); } else{ if(even(K))ans+=comb(N,K/2); else ans+=comb(N-1,(K-1)/2)*2; // 真ん中は上下どちらでも可能なので*2通り } pp(ans/4); }}