#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<ll, ll> pii;

const ll mod = 998244353;

struct mat {
	ll a[3][3];
	mat() {
		mems(a, 0);
	}
};

inline mat operator * (const mat &a, const mat &b) {
	mat res;
	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] = (res.a[i][j] + a.a[i][k] * b.a[k][j]) % mod;
			}
		}
	}
	return res;
}

inline mat qpow(mat a, ll p) {
	mat res;
	res.a[0][0] = 2;
	res.a[0][1] = 0;
	res.a[0][2] = 3;
	while (p) {
		if (p & 1) {
			res = res * a;
		}
		a = a * a;
		p >>= 1;
	}
	return res;
}

unordered_map<ll, ll> mp;
ll K;

ll F(ll m) {
	if (m == 1) {
		return 1;
	}
	if (mp.find(m) != mp.end()) {
		return mp[m];
	}
	if (m % 2 == 0) {
		return mp[m] = F(m / 2) * K % mod;
	} else {
		return mp[m] = (F(m / 2) + F(m / 2 + 1)) % mod;
	}
}

void solve() {
	ll n, m;
	scanf("%lld%lld", &n, &m);
	mat A;
	A.a[0][1] = 1;
	A.a[1][0] = A.a[1][2] = 1;
	A.a[2][0] = 1;
	mat res = qpow(A, n - 2);
	K = res.a[0][0];
	if (!m) {
		puts("1");
		return;
	}
	printf("%lld\n", F(m + 1));
}

int main() {
	int T = 1;
	// scanf("%d", &T);
	while (T--) {
		solve();
	}
	return 0;
}