#![allow(unused_imports, unused_macros)] use kyoproio::*; use std::{ collections::*, io::{self, prelude::*}, iter, mem::{replace, swap}, }; fn main() -> io::Result<()> { std::thread::Builder::new() .stack_size(64 * 1024 * 1024) .spawn(|| { run( KInput::new(io::stdin().lock()), io::BufWriter::new(io::stdout().lock()), ) })? .join() .unwrap(); Ok(()) } fn run(mut kin: I, mut out: O) { macro_rules! output { ($($args:expr),+) => { write!(&mut out, $($args),+).unwrap(); }; } macro_rules! outputln { ($($args:expr),+) => { output!($($args),+); outputln!(); }; () => { output!("\n"); if cfg!(debug_assertions) { out.flush().unwrap(); } } } let mut c = [0; 26]; for b in kin.str().bytes() { c[(b - b'a') as usize] += 1; } let mut finv = vec![1; *c.iter().max().unwrap() + 1]; for i in 2..finv.len() { finv[i] = finv[i - 1] * mod_inv(i as i64, P) % P; } let mut que = VecDeque::with_capacity(26); for &c in &c { que.push_back(finv[..=c].to_owned()); } while que.len() >= 2 { let mut f = que.pop_front().unwrap(); let mut g = que.pop_front().unwrap(); convolution(&mut f, &mut g); que.push_back(f); } let f = que.pop_front().unwrap(); let mut ans = 0; let mut fact = 1; for i in 1..f.len() { fact = (fact * i as i64) % P; ans = (ans + fact * f[i]) % P; } outputln!("{}", ans); } const P: i64 = 998244353; // 2^23 * 7 * 17 + 1 const PR: i64 = 3; pub fn dft(a: &mut [i64], inv: bool) { // Cooley–Tukey FFT debug_assert!(a.len().is_power_of_two()); let n = a.len(); for i in 0..n { let j = i.reverse_bits().wrapping_shr(n.leading_zeros() + 1); if i < j { a.swap(i, j); } } let mut w = Vec::with_capacity(n / 2); for k in (1..).map(|d| 1 << d).take_while(|&k| k <= n) { let r = if inv { mod_pow(PR, (P - 1) / k as i64, P) } else { mod_pow(PR, P - 1 - (P - 1) / k as i64, P) }; w.clear(); w.extend(std::iter::successors(Some(1), |&w| Some(w * r % P)).take(k / 2)); for ofs in (0..n).step_by(k) { for i in 0..k / 2 { let u = ofs + i; let v = ofs + i + k / 2; let t = w[i] * a[v]; a[v] = (a[u] - t).rem_euclid(P); a[u] = (a[u] + t) % P; } } } if inv { let d = mod_pow(n as i64, P - 2, P); for v in a { *v = d * *v % P; } } } pub fn convolution(a: &mut Vec, b: &mut Vec) { let n = a.len() + b.len() - 1; let m = n.next_power_of_two(); a.resize(m, 0); b.resize(m, 0); dft(a, false); dft(b, false); for (x, y) in a.iter_mut().zip(b.iter()) { *x = *x * *y % P; } dft(a, true); a.truncate(n); } pub fn extgcd(a: i64, b: i64) -> (i64, i64, i64) { if b != 0 { let (g, y, x) = extgcd(b, a.rem_euclid(b)); (g, x, y - a / b * x) } else { (a, 1, 0) } } pub fn mod_inv(x: i64, m: i64) -> i64 { extgcd(x, m).1 } pub fn mod_pow(mut a: i64, mut b: i64, m: i64) -> i64 { let mut y = 1; while b > 0 { if b & 1 == 1 { y = y * a % m; } a = a * a % m; b >>= 1; } y } // ----------------------------------------------------------------------------- pub mod kyoproio { use std::io::prelude::*; pub trait Input { fn str(&mut self) -> &str; fn input(&mut self) -> T { T::input(self) } fn iter(&mut self) -> Iter { Iter(self, std::marker::PhantomData) } fn seq>(&mut self, n: usize) -> B { self.iter().take(n).collect() } } pub struct KInput { src: R, buf: String, pos: usize, } impl KInput { pub fn new(src: R) -> Self { Self { src, buf: String::with_capacity(1 << 12), pos: 0, } } } impl Input for KInput { fn str(&mut self) -> &str { loop { if self.pos >= self.buf.len() { self.pos = 0; self.buf.clear(); if self.src.read_line(&mut self.buf).expect("io error") == 0 { return &self.buf; } } let range = self.pos ..self.buf[self.pos..] .find(|c: char| c.is_ascii_whitespace()) .map(|i| i + self.pos) .unwrap_or_else(|| self.buf.len()); self.pos = range.end + 1; if range.end > range.start { return &self.buf[range]; } } } } pub struct Iter<'a, T, I: ?Sized>(&'a mut I, std::marker::PhantomData<*const T>); impl<'a, T: InputParse, I: Input + ?Sized> Iterator for Iter<'a, T, I> { type Item = T; fn next(&mut self) -> Option { Some(self.0.input()) } } pub trait InputParse: Sized { fn input(src: &mut I) -> Self; } impl InputParse for Vec { fn input(src: &mut I) -> Self { src.str().as_bytes().to_owned() } } macro_rules! from_str_impl { { $($T:ty)* } => { $(impl InputParse for $T { fn input(src: &mut I) -> Self { src.str().parse::<$T>().expect("parse error") } })* } } from_str_impl! { String char bool f32 f64 isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 } macro_rules! tuple_impl { ($H:ident $($T:ident)*) => { impl<$H: InputParse, $($T: InputParse),*> InputParse for ($H, $($T),*) { fn input(src: &mut I) -> Self { ($H::input(src), $($T::input(src)),*) } } tuple_impl!($($T)*); }; () => {} } tuple_impl!(A B C D E F G); #[macro_export] macro_rules! kdbg { ($($v:expr),*) => { if cfg!(debug_assertions) { dbg!($($v),*) } else { ($($v),*) } } } }