#include<bits/stdc++.h>
#define int long long
#define mod 998244353 
using namespace std;
int n, m;
struct Matrix{
	int a[3][3];
	void clear()
	{
		memset(a, 0, sizeof(a));
	}
	void init()
	{
		clear();
		for(int i = 0; i < 3; i++) a[i][i] = 1;
	}
}trans, ret;
Matrix operator * (Matrix x, Matrix y)
{
	Matrix res;
	res.clear();
	for(int k = 0; k < 3; k++) for(int i = 0; i < 3; i++) for(int j = 0; j < 3; j++) (res.a[i][j] += x.a[i][k] * y.a[k][j] % mod) %= mod;
	return res;
}
Matrix operator ^ (Matrix x, int ti)
{
	Matrix res;
	res.init();
	while(ti)
	{
		if(ti & 1) res = res * x;
		x = x * x;
		ti >>= 1; 
	}
	return res;
}
// 01 10 11
int ans1;
map<int, int> mp;
int dp(int x)
{
	if(x == 0) return 1;
	else if(x == 1) return ans1;
	if(mp[x]) return mp[x];
	if(x & 1) mp[x] = dp(x / 2) * ans1 % mod;
	else mp[x] = (dp(x / 2) + dp(x / 2 - 1)) % mod;
	return mp[x];
}
signed main()
{
	scanf("%lld%lld", &n, &m);
	trans.clear();
	trans.a[0][1] = trans.a[0][2] = trans.a[1][0] = trans.a[2][1] = 1;
	ret = trans ^ n;
	ans1 = (ret.a[0][0] + ret.a[1][1] + ret.a[2][2]) % mod;
//	cout << ans1 << endl;
	printf("%lld\n", dp(m));
	return 0;
}