#include<bits/stdc++.h>
using namespace std;
#define int long long
const int mod=998244353;
map<int,int> f;
struct Matrix{
	int a[3][3];
	void init(){memset(a,0,sizeof(a));}
	void build(){init();a[0][0]=a[1][1]=a[2][2]=1;}
	Matrix operator *(const Matrix &b){
		Matrix c;c.init();
		for(int k=0;k<3;k++){
			for(int i=0;i<3;i++){
				for(int j=0;j<3;j++) c.a[i][j]=(c.a[i][j]+a[i][k]*b.a[k][j])%mod;
			}	
		}return c;
	}
}bs;
int n,m;
int sum;
int dfs(int x){
	// cerr<<x<<' ';
	if(f[x]) return f[x];
	int res=0;
	if(x&1) res=sum*dfs(x>>1)%mod;
	else res=(dfs(x>>1)+dfs((x>>1)-1))%mod;
	return f[x]=res%mod;
}
Matrix qpow(Matrix bs,int x){
	Matrix now;now.build();
	while(x){
		if(x&1) now=now*bs;
		bs=bs*bs;
		x>>=1;
	}return now;
}
signed main(){
	cin>>n>>m;
	f[0]=1;
	bs.a[0][1]=bs.a[0][2]=1;
	bs.a[1][0]=1;
	bs.a[2][1]=1;
	Matrix tmp=qpow(bs,n-2);
	sum+=tmp.a[0][0]+tmp.a[1][0];
	sum+=tmp.a[1][1]+tmp.a[2][1];
	sum+=tmp.a[0][2];
	sum%=mod;
	cout<<dfs(m);
	return 0;
}