#include <bits/stdc++.h>

using namespace std;

typedef long long LL;

const int P = 998244353;

LL a[3][3], b[3];

inline void Mul(LL a[][3], LL b[][3], LL c[][3])
{
	static LL t[3][3];
	memset(t, 0, sizeof t);
	for(int i = 0; i < 3; i ++ )
		for(int j = 0; j < 3; j ++ )
			for(int k = 0; k < 3; k ++ )
				t[i][k] = (t[i][k] + a[i][j] * b[j][k]) % P;
	memcpy(c, t, sizeof t);
}
inline void Mul(LL a[], LL b[][3], LL c[])
{
	static LL t[3];
	memset(t, 0, sizeof t);
	for(int i = 0; i < 3; i ++ )
		for(int j = 0; j < 3; j ++ )
			t[j] = (t[j] + a[i] * b[i][j]) % P;
	memcpy(c, t, sizeof t);
}
inline LL ksm(LL n)
{
	memset(a, 0, sizeof a);
	memset(b, 0, sizeof b);
	a[0][1] = a[1][2] = a[1][0] = a[2][0] = 1;
	b[0] = 1;
	while(n)
	{
		if(n & 1) Mul(b, a, b);
		Mul(a, a, a);
		n >>= 1;
	}
	return b[0];
}
LL g;

unordered_map<int, LL> f;

inline LL DP(int m)
{
	if(m == 0) return 1;
	if(f.count(m)) return f[m];
	if(m & 1) return f[m] = DP(m >> 1) * g % P;
	else return f[m] = (DP((m >> 1) - 1) + DP(m >> 1)) % P;
}

int main()
{
	int n, m;
	scanf("%d%d", &n, &m);
	g = (ksm(n) * 2 + ksm(n - 3)) % P;
	// printf("!%lld\n", g);
	printf("%lld\n", DP(m));
	return 0;
}