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 (1.42.0) (judge verdict: Accepted)

use proconio::{input, marker::Chars};
use std::collections::HashMap;

fn main() {
    input! {
        a: Chars,
    }

    let len = a.len() as u64;

    let mut map = HashMap::new();

    for c in a {
        *map.entry(c).or_insert(0) += 1;
    }

    let mut count = 0_u64;

    for (_, val) in map {
        count += (len - val) * val;
    }
    count /= 2;
    count += 1;

    println!("{}", count);
}