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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System.Collections.Generic;
using System.Linq;
using System;

public class Hello
{
    public static void Main()
    {
        var s =Console.ReadLine().Trim();
        var sL = s.Length;
        var res = new List<string>();
        for (int i = 0; i < sL - 1; i++)
            for (int j = i + 1; j < sL; j++)
                res.Add(revS(s, i, j));
        var ans = res.Distinct().Count();
        Console.WriteLine(ans);
    }
    public static string revS (string s , int a , int b)
    {
        var w2 = string.Join("", s.Substring(a, b - a + 1).ToCharArray().Reverse());
        return s.Substring(0, a) + w2 + s.Substring(b + 1);
    }
}