#include <bits/stdc++.h>
#define int long long
using namespace std;
const int p=998244353;
typedef array<array<int,3>,3>matrix;
matrix operator *(const matrix &a,const matrix &b)
{
	matrix r={0,0,0,0,0,0,0,0,0};
	for(int i=0;i<3;i++)
	{
		for(int j=0;j<3;j++)
		{
			for(int k=0;k<3;k++)
			{
				r[i][j]=(r[i][j]+a[i][k]*b[k][j])%p;
			}
		}
	}
	return r;
}
map<int,int>dp;
int n,m,z;
int f(int x)
{
	if(x<=1)
	{
		return x?z:1;
	}
	if(dp.count(x))
	{
		return dp[x];
	}
	if(x&1)
	{
		return dp[x]=z*f(x/2)%p;
	}
	return dp[x]=(f(x/2)+f(x/2-1))%p;
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	matrix I={1,0,0,0,1,0,0,0,1},T={0,1,1,1,0,0,0,1,0};
	for(int k=n;k;k>>=1,T=T*T)
	{
		if(k&1)
		{
			I=I*T;
		}
	}
	z=(I[0][0]+I[1][1]+I[2][2])%p;
	cout<<f(m)<<flush;
	return 0;
}