#include #include #include #include template struct ModInt { using lint = long long; int val; // constructor ModInt(lint v = 0) : val(v % MOD) { if (val < 0) val += MOD; }; // unary operator ModInt operator+() const { return ModInt(val); } ModInt operator-() const { return ModInt(MOD - val); } ModInt inv() const { return this->pow(MOD - 2); } // arithmetic ModInt operator+(const ModInt& x) const { return ModInt(*this) += x; } ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; } ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; } ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; } ModInt pow(lint n) const { auto x = ModInt(1); auto b = *this; while (n > 0) { if (n & 1) x *= b; n >>= 1; b *= b; } return x; } // compound assignment ModInt& operator+=(const ModInt& x) { if ((val += x.val) >= MOD) val -= MOD; return *this; } ModInt& operator-=(const ModInt& x) { if ((val -= x.val) < 0) val += MOD; return *this; } ModInt& operator*=(const ModInt& x) { val = lint(val) * x.val % MOD; return *this; } ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); } // compare bool operator==(const ModInt& b) const { return val == b.val; } bool operator!=(const ModInt& b) const { return val != b.val; } bool operator<(const ModInt& b) const { return val < b.val; } bool operator<=(const ModInt& b) const { return val <= b.val; } bool operator>(const ModInt& b) const { return val > b.val; } bool operator>=(const ModInt& b) const { return val >= b.val; } // I/O friend std::istream& operator>>(std::istream& is, ModInt& x) noexcept { lint v; is >> v; x = v; return is; } friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; } }; template struct Combination { int max_n; std::vector f, invf; explicit Combination(int n) : max_n(n), f(n + 1), invf(n + 1) { f[0] = 1; for (int i = 1; i <= n; ++i) { f[i] = f[i - 1] * i; } invf[max_n] = f[max_n].inv(); for (int i = max_n - 1; i >= 0; --i) { invf[i] = invf[i + 1] * (i + 1); } } T fact(int n) const { return n < 0 ? T(0) : f[n]; } T invfact(int n) const { return n < 0 ? T(0) : invf[n]; } T perm(int a, int b) const { return a < b || b < 0 ? T(0) : f[a] * invf[a - b]; } T binom(int a, int b) const { return a < b || b < 0 ? T(0) : f[a] * invf[a - b] * invf[b]; } }; template struct NumberTheoreticalTransform { using mint = ModInt; using mints = std::vector; std::vector zetas; explicit NumberTheoreticalTransform() { int exp = MOD - 1; while (true) { mint zeta = mint(Root).pow(exp); zetas.push_back(zeta); if (exp % 2 != 0) break; exp /= 2; } } // ceil(log_2 n) static int clog2(int n) { int k = 0; while ((1 << k) < n) ++k; return k; } // cooley-tukey algorithm without bit reverse void ntt(mints& f, bool isinv) const { int n = f.size(); auto zeta = zetas[clog2(n)]; if (isinv) zeta = zeta.inv(); for (int b = n; b > 1; b >>= 1, zeta *= zeta) { mint zetapow = 1; for (int i = 0; i < b / 2; ++i) { for (int j = i; j < n; j += b) { auto l = f[j], r = f[j + b / 2]; f[j] = l - r * zetapow; f[j + b / 2] = l + r * zetapow; } zetapow *= zeta; } } if (isinv) { auto ninv = mint(f.size()).inv(); for (auto& x : f) x *= ninv; } } mints convolute(mints f, mints g) const { int fsz = f.size(), gsz = g.size(); // simple convolution in small cases if (std::min(fsz, gsz) < 30) { mints ret(fsz + gsz - 1, 0); for (int i = 0; i < fsz; ++i) { for (int j = 0; j < gsz; ++j) { ret[i + j] += f[i] * g[j]; } } return ret; } int n = 1 << clog2(fsz + gsz - 1); f.resize(n, mint(0)); g.resize(n, mint(0)); ntt(f, false); ntt(g, false); for (int i = 0; i < n; ++i) f[i] *= g[i]; ntt(f, true); f.resize(fsz + gsz - 1); return f; } }; constexpr int MOD = 998244353; using mint = ModInt; const Combination C(300000); const NumberTheoreticalTransform NTT; void solve() { std::string s; std::cin >> s; std::vector cnt(26, 0); for (char c : s) ++cnt[c - 'a']; std::vector f{1}; for (auto d : cnt) { std::vector g(d + 1); for (int i = 0; i <= d; ++i) g[i] = C.invfact(i); f = NTT.convolute(f, g); } mint ans = 0; for (int i = 1; i < (int)f.size(); ++i) { ans += f[i] * C.fact(i); } std::cout << ans << "\n"; } int main() { std::cin.tie(nullptr); std::ios::sync_with_stdio(false); solve(); return 0; }