#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <array>
using namespace std;

using ll = long long;

constexpr ll MOD = 998244353ll;

int n, m;
map<int, ll> ans;

struct Matrix
{
	array<array<ll, 3>, 3> v;
	array<ll, 3>& operator[](const int& x)
	{
		return v[x];
	}
	friend Matrix operator*(Matrix a, Matrix b)
	{
		Matrix 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++) c[i][j] += a[i][k] * b[k][j];
				c[i][j] %= MOD;
			}
		}
		return c;
	}
	friend Matrix operator^(Matrix a, int b)
	{
		Matrix res = a, base = a;
		b--;
		while (b)
		{
			if (b & 1) res = res * base;
			base = base * base;
			b >>= 1;
		}
		return res;
	}
}mt, res;

ll t;

inline ll f(int x)
{
	if (ans.count(x)) return ans[x];
	if (!x)
	{
		return 1;
	}
	else if (x == 1) return t;
	else
	{
		ll ret = ((x & 1) ? t * f(x / 2) % MOD : (f(x / 2) + f(x / 2 - 1)) % MOD);
		return (ans[x] = ret);
	}
}

int main()
{
	ios::sync_with_stdio(0), cin.tie(0);
	cin >> n >> m;
	mt[0][2] = mt[1][0] = mt[1][2] = mt[2][1] = 1;
	res[0][0] = 3, res[0][1] = 0, res[0][2] = 2;
	res = res * (mt ^ (n - 2));
	t = res[0][2];
	cout << f(m) << "\n";
	return 0;
}