n,m<=1e6

 

 卡常即可100分

#pragma GCC optimize(2)#pragma GCC optimize(3)#pragma GCC optimize("Ofast")#include
     
      #include
      
       #include
       
        #include
        
         using namespace std;const int md=998244353,N=4000005;int n,m,i,j,f[5005][5005],s[5005][5005],a[N],b[N],g[N],h[N],rt[N],lmt,len,ome[N],rome[N],w1[N],w2[N],inv[N],jc[N],rjc[N],ans;inline int pw(int a,int b){    int rtn=1;    while(b)    {        if(b&1)            rtn=1ll*rtn*a%md;        a=1ll*a*a%md;        b>>=1;    }    return rtn;}inline void ntt(int a[N],bool t){    for(int i=0;i
         
          >1;        for(int i=0;i
          
           >1,i; merge(l,mid); merge(mid+1,r); lmt=0; while((1<
           
            <=r-l+2) ++lmt; len=1<