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 Kotlin (1.3.71) (judge verdict: Accepted)

// https://atcoder.jp/contests/agc019/tasks/agc019_b

fun main() {
    agc019b()
}

fun agc019b() {
    val a = readLine()!!
    val n = a.length.toLong()
    var count = (n - 1) * n / 2 + 1
    val appear = a.groupingBy { it }.eachCount()
    for (value in appear.values.map { it.toLong() }) {
        count -= (value * (value - 1) / 2)
    }
    println(count)
}