#include <cstdio>
#include <unordered_map>

typedef long long ll;
const int mod = 998244353;
std::unordered_map<ll, int> mp;
struct Matrix {
	int a[3][3];
	Matrix operator * (const Matrix &rhs) const {
		Matrix c;
		for (int i = 0; i < 3; ++ i)
		for (int j = 0; j < 3; ++ j)
			c.a[i][j] = (1ll * a[i][0] * rhs.a[0][j] + 1ll * a[i][1] * rhs.a[1][j] +
			1ll * a[i][2] * rhs.a[2][j]) % mod;
		return c;
	}
} mat, E;
int solve(int n, int m) {
	if (m < 0) return 0;
	if (m == 0) return 1;
	ll id = 1ll * n * 1000000001 + m;
	if (mp.count(id)) return mp[id];
	if (m % 2 == 0) return (solve(n, m / 2) + solve(n, m / 2 - 1)) % mod;
	Matrix res = E, a = mat; int b = n;
	while (b) {
		if (b & 1) res = res * a;
		a = a * a, b >>= 1;
	}
	return mp[id] = 1ll * (1ll * res.a[0][0] + 1ll * res.a[1][1] + 1ll * res.a[2][2]) % mod * solve(n, m / 2) % mod;
}

int main() {
	mat.a[0][1] = mat.a[0][2] = mat.a[1][0] = mat.a[2][1] = E.a[0][0] = E.a[1][1] = E.a[2][2] = 1;
	int n, m; scanf("%d%d", &n, &m); printf("%d", solve(n, m)); return 0;
}