记录编号	616868	评测结果	AAAAAAAAAA
题目名称	and I am home	最终得分	100
用户昵称	RpUtl	是否通过	通过
代码语言	C++	运行时间	0.033 s
提交时间	2026-07-02 11:20:37	内存使用	3.74 MiB

#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
const int N = 2e6 + 10;
typedef long long ll;
const int G = 3;
ll R[N];
ll ksm(ll a, ll b) {
	if (b < 0) b += mod - 1;
	ll ans = 1;
	while (b) {
		if (b & 1) ans = ans * a % mod;
		a = a * a % mod;
		b >>= 1;
	}
	return ans;
}
void init(int n) {
	for (int i = 0; i < n; i++) {
		R[i] = (R[i >> 1] >> 1) + ((i & 1) ? (n >> 1) : 0);
	}
}
void NTT(ll *f, int n, int ok) {
	for (int i = 0; i < n; i++) {
		if (R[i] < i) swap(f[i], f[R[i]]);
	}
	for (int i = 2; i <= n; i <<= 1) {
		int g = ksm(G, (mod - 1) / i * ok);
		for (int j = 0; j < n; j += i) {
			ll w = 1, u, v;
			for (int k = j; k < j + (i >> 1); k++) {
				u = f[k], v = f[k + (i >> 1)] * w % mod;
				f[k] = (u + v) % mod, f[k + (i >> 1)] = (u - v + mod) % mod;
				w = w * g % mod;
			}
		}
	}
	if (ok == -1) {
		int inv = ksm(n, mod - 2);
		for (int i = 0; i < n; i++) {
			f[i] = f[i] * inv % mod;
		}
	}
}
ll t[N], h[N], m;
void inv(ll *f, int n) {
	h[0] = ksm(f[0], mod - 2);
	for (m = 1; m <= n; m <<= 1);
	for (int i = 2, L; i <= m; i <<= 1) {
		for (int j = 0; j < i; j++) t[j] = f[j];
		for (int j = (i >> 1); j < i; j++) h[j] = 0;
		L = (i << 1); init(L); NTT(t, L, 1), NTT(h, L, 1);
		for (int j = 0; j < L; j++) {
			h[j] = h[j] * (2ll - h[j] * t[j] % mod + mod) % mod;
		}
		NTT(h, L, -1);
	}
	for (int i = 0; i < n; i++) f[i] = h[i];
	return;
}
ll g[N], f[N], n, fac[N], invf[N], ans, pw[N];
ll C(ll n, ll m) {
	return fac[n] * invf[m] % mod * invf[n - m] % mod; 
}
int main() {
	freopen("home.in", "r", stdin);
	freopen("home.out", "w", stdout);
	cin >> n;
	fac[0] = invf[0] = pw[0] = 1;
	for (int i = 1; i <= n; i++) {
		fac[i] = fac[i - 1] * i % mod;
		invf[i] = ksm(fac[i], mod - 2);
		pw[i] = pw[i - 1] * 4 % mod;
	}
	for (int i = 1; i <= n; i++) {
		if (i & 1) continue;
		g[i] = C(i, i / 2) * C(i, i / 2) % mod;
	}
	for (int i = 1; i <= n; i++) f[i] = g[i];
	f[0]++; inv(f, n); int L;
	for (L = 1; L <= (n << 1); L <<= 1);
	init(L), NTT(g, L, 1), NTT(f, L, 1);
	for (int i = 0; i < L; i++) f[i] = f[i] * g[i] % mod;
	NTT(f, L, -1);
	ans = (n + 1) * pw[n] % mod;
	for (int i = 1; i <= n; i++) {
		ans -= f[i] * pw[n - i] % mod * (n - i + 1) % mod; 
		ans %= mod;
	}
	ans = (ans % mod + mod) % mod;
	cout << ans << '\n';
	return 0;
}