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)

use std::io::*;
use std::str::*;
use std::cmp::*;
use std::fmt;



fn main() {
    let mut s:String = read();
    let c = s.chars().collect::<Vec<char>>();
    let mut cnt:Vec<i64> =vec![0;30];
    for i in 0..c.len(){
        cnt[(c[i] as usize)-('a' as usize)] += 1;
    }
    let mut len:i64 = c.len() as i64;
    let mut ans:i64 = len*(len-1)/2;
    for i in 0..26{
        ans -= cnt[i]*(cnt[i]-1)/2;
    }
    println!("{}",ans+1)
}

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let s = stdin.bytes().map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect::<String>();
    s.parse::<T>().unwrap_or_else(|_| panic!("Faild to parse {}", s))
}