#include <bits/stdc++.h>
using namespace std;
#define int long long
#define MOD 998244353
int n, m;
struct node {
	//01 10 11
	//010
	//101
	//011
	//110
	//a[0][1] = a[1][0] = a[0][2] = a[2][1] = 1;
	int a[3][3];
	node() {
		memset(a, 0, sizeof(a));
	}
	node operator*(const node &b) const {
		node 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] += a[i][k] * b.a[k][j] % MOD;
					res.a[i][j] %= MOD;
				}
			}
		}
		return res;
	}
} base, res;
node qpow(node x, int y) {
	node res;
	res.a[0][0] = res.a[1][1] = res.a[2][2] = 1;
	while (y) {
		if (y & 1) {
			res = res * x;
		}
		x = x * x;
		y >>= 1;
	}
	return res;
}
map<int, int> mp;
int dfs(int x) {
	if (!x) {
		return 1;
	}
	if (x == 1) {
		return (res.a[0][0] + res.a[1][1] + res.a[2][2]) % MOD;
	}
	if (mp.count(x)) {
		return mp[x];
	}
	if (x % 2 == 0) {
		return (dfs(x / 2) + dfs(x / 2 - 1)) % MOD;
	}
	int g = dfs(x / 2);
	return g * (res.a[0][0] + res.a[1][1] + res.a[2][2]) % MOD; 
}
signed main() {
	cin >> n >> m;
	base.a[0][1] = base.a[1][0] = base.a[0][2] = base.a[2][1] = 1;
	res = qpow(base, n);
	cout << dfs(m);
	return 0;
}