#include #include using namespace std; using mint=atcoder::modint998244353; template struct combination { combination(int n=0):inner_fac(1,1),inner_finv(1,1){init(n);} mint fac(int n) { init(n); return inner_fac[n]; } mint finv(int n) { init(n); return inner_finv[n]; } mint inv(int n) { if(n==0)return 0; init(n); return inner_fac[n-1]*inner_finv[n]; } mint C(int n, int r) { if(r<0)return 0; if(n<0) { n=-n; mint res=C(n-1+r,r); if(r&1)res=-res; return res; } if(ninner_fac,inner_finv; void init(int n) { int sz=inner_fac.size(); if(sz>n)return; n=min(max(n,2*sz),bound); inner_fac.resize(n+1); inner_finv.resize(n+1); for(int i=sz;i<=n;i++)inner_fac[i]=inner_fac[i-1]*i; inner_finv[n]=inner_fac[n].inv(); for(int i=n;i>sz;i--)inner_finv[i-1]=inner_finv[i]*i; } }; combinationC; mint narayana(int n, int k) { return C.C(n,k)*C.C(n,k-1)*C.inv(n); } int main() { int N,K; cin>>N>>K; mint ans=0; for(int j=1;j<=K;j++)ans+=C.C(2*K+N-2*j+1,N-2*j+1)*narayana(K,j); cout<<(K==0?mint(1):ans).val()<