#include<bits/stdc++.h>
#define Yzl unsigned long long
#define fi first
#define se second
#define pi pair<int,int>
#define mp make_pair
#define lob lower_bound
#define pb emplace_back
typedef long long LL;

using namespace std;

const Yzl Lty=20120712;

const int MAXN=40,P=998244353;
int n,m;
int f[MAXN][2];
LL fad(LL x,LL y) {
	return (x+y>=P?x+y-P:x+y);
}
struct Matrix {
	int a[3][3];
	Matrix() {
		memset(a,0,sizeof(a));
	}
	friend Matrix operator *(Matrix a,Matrix b) {
		Matrix ls;
		for(int i=0;i<3;++i) for(int k=0;k<3;++k) for(int j=0;j<3;++j) {
			ls.a[i][j]=fad(ls.a[i][j],(LL)a.a[i][k]*b.a[k][j]%P);
		} return ls;
	}
}Ans,zy;
int main () {
	scanf("%d%d",&n,&m);
	Ans.a[0][1]=2; Ans.a[0][2]=3;
	zy.a[1][0]=1; zy.a[2][1]=1; zy.a[0][2]=1; zy.a[1][2]=1;
	int ls=n-3;
	while(ls) {
		if(ls&1) Ans=Ans*zy;
		zy=zy*zy; ls>>=1;
	}
	f[0][0]=1; LL coef=Ans.a[0][2];
//	cout<<coef<<' ';
	for(int i=1;i<=31;++i) {
		if((m>>(i-1))&1) {
			f[i][0]=fad((LL)f[i-1][0]*coef%P,f[i-1][1]);
			f[i][1]=f[i-1][1];
		} else {
			f[i][0]=f[i-1][0];
			f[i][1]=fad((LL)f[i-1][1]*coef%P,f[i-1][0]);
		}
	} printf("%d\n",f[31][0]);
	return 0;
}