#include<bits/stdc++.h>
#define int long long
#define rep(i,l,r) for(int i=(l);i<=(r);i++)
#define per(i,l,r) for(int i=(l);i>=(r);i--)
using namespace std;
int rd() {int x=0,f=1;char c=getchar();while(!isdigit(c))f=c=='-'?-1:f,c=getchar();while(isdigit(c))x=x*10+(c^48),c=getchar();return x*f;}
const int mod=998244353;
int res;
struct matrix {
    int a[4][4];
    void clear() {memset(a,0,sizeof(a));}
    void init() {clear();rep(i,0,3)a[i][i]=1;}
}trs;
matrix operator*(matrix x,matrix y) {
    matrix z;z.clear();
    rep(i,0,3) rep(j,0,3) rep(k,0,3) (z.a[i][j]+=x.a[i][k]*y.a[k][j])%=mod;
    return z;
}
matrix qp(matrix a,int k) {matrix r;r.init();for(;k;k>>=1,a=a*a)if(k&1)r=r*a;return r;}
int dfs(int m) {
    if(!m) return 1;
    if(m&1) return res*dfs(m/2)%mod;
    else return (dfs(m/2)+dfs(m/2-1))%mod;
}
signed main() {
    int n=rd();
    trs.a[1][2]=1;
    trs.a[1][3]=1;
    trs.a[2][1]=1;
    trs.a[3][2]=1;
    rep(i,0,3) {
        matrix mat;mat.clear();mat.a[0][i]=1;
        mat=mat*qp(trs,n);
        (res+=mat.a[0][i])%=mod;
    }
    printf("%lld\n",dfs(rd()));
    return 0;
}