#include "bits/stdc++.h" #ifdef DAN13 #include "../lib/debug.h" #else #define dbg(...) 69 #endif using namespace std; // containers using ll = long long; #define af(x) x.begin(), x.end() #define pb push_back // rng mt19937 g1(chrono::steady_clock::now().time_since_epoch().count()); ll randint(ll a, ll b) { return uniform_int_distribution(a, b)(g1); } template void rem_dup(vector &v) { sort(af(v)); v.resize(unique(af(v)) - v.begin()); } template bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; } template bool ckmax(T &a, const T &b) { return b > a ? a = b, 1 : 0; } const int MOD1 = 1e9 + 7; const int MOD2 = 998244353; template T inverse(T a, T m) { T u = 0, v = 1; while (a != 0) { T t = m / a; m -= t * a; swap(a, m); u -= t * v; swap(u, v); } assert(m == 1); return u; } template class Modular { public: using Type = typename decay::type; constexpr Modular() : value() {} template Modular(const U& x) { value = normalize(x); } template static Type normalize(const U& x) { Type v; if (-mod() <= x && x < mod()) v = static_cast(x); else v = static_cast(x % mod()); if (v < 0) v += mod(); return v; } const Type& operator()() const { return value; } template explicit operator U() const { return static_cast(value); } constexpr static Type mod() { return T::value; } Modular& operator+=(const Modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; } Modular& operator-=(const Modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; } template Modular& operator+=(const U& other) { return *this += Modular(other); } template Modular& operator-=(const U& other) { return *this -= Modular(other); } Modular& operator++() { return *this += 1; } Modular& operator--() { return *this -= 1; } Modular operator++(int) { Modular result(*this); *this += 1; return result; } Modular operator--(int) { Modular result(*this); *this -= 1; return result; } Modular operator-() const { return Modular(-value); } Modular operator+() const { return Modular(value); } // controversial? template typename enable_if::Type, int>::value, Modular>::type& operator*=(const Modular& rhs) { #ifdef _WIN32 uint64_t x = static_cast(value) * static_cast(rhs.value); uint32_t xh = static_cast(x >> 32), xl = static_cast(x), d, m; asm( "divl %4; \n\t" : "=a"(d), "=d"(m) : "d"(xh), "a"(xl), "r"(mod())); value = m; #else value = normalize(static_cast(value) * static_cast(rhs.value)); #endif return *this; } template typename enable_if::Type, long long>::value, Modular>::type& operator*=(const Modular& rhs) { long long q = static_cast(static_cast(value) * rhs.value / mod()); value = normalize(value * rhs.value - q * mod()); return *this; } template typename enable_if::Type>::value, Modular>::type& operator*=(const Modular& rhs) { value = normalize(value * rhs.value); return *this; } Modular& operator/=(const Modular& other) { return *this *= Modular(inverse(other.value, mod())); } friend const Type& abs(const Modular& x) { return x.value; } template friend bool operator==(const Modular& lhs, const Modular& rhs); template friend bool operator<(const Modular& lhs, const Modular& rhs); template friend V& operator>>(V& stream, Modular& number); private: Type value; }; template bool operator==(const Modular& lhs, const Modular& rhs) { return lhs.value == rhs.value; } template bool operator==(const Modular& lhs, U rhs) { return lhs == Modular(rhs); } template bool operator==(U lhs, const Modular& rhs) { return Modular(lhs) == rhs; } template bool operator!=(const Modular& lhs, const Modular& rhs) { return !(lhs == rhs); } template bool operator!=(const Modular& lhs, U rhs) { return !(lhs == rhs); } template bool operator!=(U lhs, const Modular& rhs) { return !(lhs == rhs); } template bool operator<(const Modular& lhs, const Modular& rhs) { return lhs.value < rhs.value; } template Modular operator+(const Modular& lhs, const Modular& rhs) { return Modular(lhs) += rhs; } template Modular operator+(const Modular& lhs, U rhs) { return Modular(lhs) += rhs; } template Modular operator+(U lhs, const Modular& rhs) { return Modular(lhs) += rhs; } template Modular operator-(const Modular& lhs, const Modular& rhs) { return Modular(lhs) -= rhs; } template Modular operator-(const Modular& lhs, U rhs) { return Modular(lhs) -= rhs; } template Modular operator-(U lhs, const Modular& rhs) { return Modular(lhs) -= rhs; } template Modular operator*(const Modular& lhs, const Modular& rhs) { return Modular(lhs) *= rhs; } template Modular operator*(const Modular& lhs, U rhs) { return Modular(lhs) *= rhs; } template Modular operator*(U lhs, const Modular& rhs) { return Modular(lhs) *= rhs; } template Modular operator/(const Modular& lhs, const Modular& rhs) { return Modular(lhs) /= rhs; } template Modular operator/(const Modular& lhs, U rhs) { return Modular(lhs) /= rhs; } template Modular operator/(U lhs, const Modular& rhs) { return Modular(lhs) /= rhs; } template Modular power(const Modular& a, const U& b) { assert(b >= 0); Modular x = a, res = 1; U p = b; while (p > 0) { if (p & 1) res *= x; x *= x; p >>= 1; } return res; } template bool IsZero(const Modular& number) { return number() == 0; } template string to_string(const Modular& number) { return to_string(number()); } // U == std::ostream? but done this way because of fastoutput template U& operator<<(U& stream, const Modular& number) { return stream << number(); } // U == std::istream? but done this way because of fastinput template U& operator>>(U& stream, Modular& number) { typename common_type::Type, long long>::type x; stream >> x; number.value = Modular::normalize(x); return stream; } constexpr int MOD = 998244353; using mi = Modular::type, MOD>>; typedef vector vmi; vmi fact, inv_fact; mi choose(int n, int k) { if (k < 0 || k > n) { return 0; } if (fact.empty()) { fact.emplace_back(1); inv_fact.emplace_back(1); } while ((int) fact.size() < n + 1) { fact.push_back(fact.back() * (int) fact.size()); inv_fact.push_back(1 / fact.back()); } return fact[n] * inv_fact[k] * inv_fact[n - k]; } void solve() { // sum_{i=2}^n-2 ((n-1) * i * (i-2)! * n-i * (n - i - 2)!)^-2 // sum_{i=2}^n-2 int n; cin >> n; choose(n, 0); mi ans = 0; for (int i = 2; i <= n - 2; i++) { mi cur = (mi)(n - 1) * (mi)i * (n - i) * fact[i - 2] * fact[n - i - 2]; cur *= cur; ans += 1 / cur; } cout << ans * fact[n] * fact[n] << '\n'; } int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); int tests = 1; // cin >> tests; for (int i = 1; i <= tests; i++) { solve(); } }