Problem:
Score : 500 points

Problem Statement

You have a string A = A_1 A_2 ... A_n consisting of lowercase English letters.

You can choose any two indices i and j such that 1 \leq i \leq j \leq n and reverse substring A_i A_{i+1} ... A_j.

You can perform this operation at most once.

How many different strings can you obtain?

Constraints

1 \leq |A| \leq 200,000

A consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

A

Output

Print the number of different strings you can obtain by reversing any substring in A at most once.

Sample Input 1

aatt

Sample Output 1

5

You can obtain aatt (don't do anything), atat (reverse A[2..3]), atta (reverse A[2..4]), ttaa (reverse A[1..4]) and taat (reverse A[1..3]).

Sample Input 2

xxxxxxxxxx

Sample Output 2

1

Whatever substring you reverse, you'll always get xxxxxxxxxx.

Sample Input 3

abracadabra

Sample Output 3

44

Solution in Rust (1.15.1) (judge verdict: Accepted)

#[allow(unused_imports)]
use std::io::{self, BufRead};
#[allow(unused_imports)]
use std::cmp::{min, max};

#[allow(dead_code)]
fn readln_to_vec<T>(buf: &mut BufRead) -> Vec<T> 
where T: std::str::FromStr,
      <T as std::str::FromStr>::Err: std::fmt::Debug
{
    let mut s = String::new();
    buf.read_line(&mut s).unwrap();
    s.split(" ")
        .map(|x| x.trim())
        .filter(|x| !x.is_empty())
        .filter_map(|x| x.parse().ok())
        .collect()
}

#[allow(dead_code)]
fn readln_to<T>(buf: &mut BufRead) -> T
where T: std::str::FromStr + std::clone::Clone,
      <T as std::str::FromStr>::Err: std::fmt::Debug
{
    readln_to_vec::<T>(buf)[0].clone()
}

#[allow(unused_macros)]
macro_rules! readln_to_tuple {
    (
        $bufRead: expr, ( $( $t: ty ),* )
    ) => (
        {
            let buf: &mut BufRead = $bufRead;
            let ln = readln_to_vec::<String>(buf);
            let mut i = ln.into_iter();
            ( $( i.next().unwrap().parse::<$t>().unwrap() ),* )
        }
        )
}


fn main() {
    let stdin = io::stdin();
    let mut stdin = stdin.lock();
    let stdin = &mut stdin;

    let a: String = readln_to(stdin);
    let a = a.as_bytes();
    let mut c = [0; 26];
    let mut ans = 1;
    for i in 0..a.len() {
        ans += i - c[a[i] as usize -'a' as usize];
        c[a[i] as usize - 'a' as usize] += 1;
    }
    println!("{}", ans);
}