#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
using ll=long long;
using pii=pair<int,int>;
using vi=vector<int>;
using vl=vector<ll>;
#define pb push_back
#define all(a) begin(a),end(a)

const int N=300010,MOD=998244353;
const char en='\n';
const ll LLINF=1ll<<60;

int mul(int a,int b)
{
	return a*1ll*b%MOD;
}

int add(int a,int b)
{
	if (a+b>=MOD) return a+b-MOD;
	return a+b;
}

void ad(int&a,int b)
{
	a+=b;
	if (a>=MOD) a-=MOD;
}

int n,m;

using mat=array<array<int,3>,3>;
mat mno,id;

mat mul(mat a,mat b)
{
	mat c;
	for (int i=0;i<3;++i) for (int j=0;j<3;++j)
	{
		c[i][j]=0;
		for (int k=0;k<3;++k) ad(c[i][j],mul(a[i][k],b[k][j]));
	}
	return c;
}

mat pot(mat a,int k)
{
	if (k==0) return id;
	mat r=pot(a,k/2);
	r=mul(r,r);
	if (k%2) r=mul(r,a);
	return r;
}

int f(int x)
{
	return pot(mno,x)[1][1];
}

int dp[2][50];

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	id[0][0]=1;
	id[1][1]=1;
	id[2][2]=1;
	mno[0][1]=1;
	mno[0][2]=1;
	mno[1][0]=1;
	mno[2][1]=1;
	cin>>n>>m;
	int ko=add(mul(2,f(n-2)),mul(3,f(n-3)));
	dp[0][30]=1;
	for (int i=29;i>=0;--i)
	{
		ad(dp[(m>>i)&1][i],dp[1][i+1]); //add 2
		ad(dp[(m>>i)&1][i],dp[0][i+1]); //add 0
		if ((m>>i)&1)
		{
			ad(dp[0][i],mul(ko,dp[0][i+1])); //add 1
		}
		else
		{
			ad(dp[1][i],mul(ko,dp[1][i+1])); //add 1
		}
	}
	cout<<dp[0][0]<<en;
}