pub mod scanner { pub struct Scanner { buf: Vec, } impl Scanner { pub fn new() -> Self { Self { buf: vec![] } } pub fn new_from(source: &str) -> Self { let source = String::from(source); let buf = Self::split(source); Self { buf } } pub fn next(&mut self) -> T { loop { if let Some(x) = self.buf.pop() { return x.parse().ok().expect(""); } let mut source = String::new(); std::io::stdin().read_line(&mut source).expect(""); self.buf = Self::split(source); } } fn split(source: String) -> Vec { source .split_whitespace() .rev() .map(String::from) .collect::>() } } } use crate::scanner::Scanner; use std::io::Write; fn main() { let mut scanner = Scanner::new(); let out = std::io::stdout(); let mut out = std::io::BufWriter::new(out.lock()); let t: usize = 1; for _ in 0..t { solve(&mut scanner, &mut out); } } fn solve(scanner: &mut Scanner, out: &mut std::io::BufWriter) { let s: Vec = scanner.next::().chars().map(|c| c).collect(); let mut count = vec![0usize; 26]; let mut ans = 0usize; for &c in s.iter() { let d = c as usize - 'A' as usize; for x in 0..26 { if x == d { continue; } if count[x] >= 2 { ans += count[x] * (count[x] - 1) / 2; } } count[d] += 1; } writeln!(out, "{}", ans).unwrap(); }