#include<bits/stdc++.h>
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
#define pii pair<ll,ll>
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define per(i,a,b) for(ll i=(a);i>=(b);--i)
using namespace std;
bool Mbe;
ll read(){
    ll x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
void write(ll x){
    if(x<0)putchar('-'),x=-x;
    if(x>9)write(x/10);
    putchar(x%10+'0');
}
const ll Mod=998244353;
ll n,m;
struct M{
    ll a[8][8];
    void clear(){memset(a,0,sizeof(a));}
}T;
M operator*(const M&x,const M&y){
    M z;z.clear();
    rep(i,0,7){
        rep(k,0,7){
            rep(j,0,7)z.a[i][j]=(z.a[i][j]+x.a[i][k]*y.a[k][j])%Mod;
        }
    }
    return z;
}
M pw(M x,ll p){
    M res;res.clear();
    rep(i,0,7)res.a[i][i]=1;
    while(p){
        if(p&1)res=res*x;
        x=x*x,p>>=1;
    }
    return res;
}
unordered_map<ll,ll>mp;
ll solve(ll m){
    if(!m)return 1;
    if(mp.count(m))return mp[m];
    if(m==1){
        T.clear();
        T.a[2][5]=1,T.a[3][6]=1,T.a[5][2]=1,T.a[5][3]=1,T.a[6][5]=1;
        T=pw(T,n);
        return mp[m]=(T.a[2][2]+T.a[3][3]+T.a[5][5]+T.a[6][6])%Mod;
    }
    if(!(m&1))return mp[m]=(solve(m>>1)+solve((m>>1)-1))%Mod;
    return mp[m]=solve(1)*solve(m>>1)%Mod;
}
bool Med;
int main(){
    cerr<<fabs(&Med-&Mbe)/1048576.0<<"MB\n";
    n=read(),m=read();
    write(solve(m));
    cerr<<"\n"<<clock()*1.0/CLOCKS_PER_SEC*1000<<"ms\n";
    return 0;
}