// Author: YE Minghan
#include<bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "templates/debug.h"
#else
#define dbg(...) (void)0
#define msg(...) (void)0
#endif
#define ll long long
#define endl '\n'
#define PB emplace_back
#define PPB pop_back
#define MP make_pair
#define ALL(Name) Name.begin(),Name.end()
#define PII pair<int,int>
#define VI vector<int>
#define GI greater<int>
#define fi first
#define se second

const int MOD=998244353;
int n,m;
struct mat
{
	int a[3][3];
	mat operator*(const mat &rhs)const
	{
		mat t;memset(t.a,0,sizeof(t.a));
		for(int i=0;i<3;i++)
			for(int k=0;k<3;k++)
				for(int j=0;j<3;j++)
					t.a[i][j]=(t.a[i][j]+1ll*a[i][k]*rhs.a[k][j])%MOD;
		return t;
	}
	mat operator^(int y)const
	{
		mat t=*this,x=t;
		y--;
		while(y)
		{
			if(y&1)t=t*x;
			x=x*x,y>>=1ll;
		}
		return t;
	}
}trs;
int C;
map<int,int>fs;
int f(int m)
{
	if(!m)return 1;
	if(fs.count(m))return fs[m];
	return fs[m]=m&1?1ll*C*f(m>>1)%MOD:(f(m>>1)+f((m>>1)-1))%MOD;
}

int main()
{
	ios::sync_with_stdio(false),cin.tie(nullptr);
//	int _;cin>>_;while(_--)

	cin>>n>>m;
	trs.a[0][1]=trs.a[1][0]=trs.a[1][2]=trs.a[2][0]=1;
	trs=trs^n;
	C=(0ll+trs.a[0][0]+trs.a[1][1]+trs.a[2][2])%MOD;
	cout<<f(m);

	return 0;
}