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;
using System.Linq;//リストの使用
using System.Collections.Generic;
class Program
{
	static void Main()
	{
    string ss = Console.ReadLine();
    int[] s = ss.Select(c => c - 'a').ToArray();
		long answer = 0;
    long[] alphaCount = new long[26];

    answer = ss.Length*(ss.Length-1)/2 + 1;
    for(long i = 0; i < ss.Length; i++)
    {
      alphaCount[s[i]]++;
    }
    for(long i = 0; i < 26; i++)
    {
      answer -= alphaCount[i]*(alphaCount[i]-1)/2;
    }
    
		Console.WriteLine(answer);//WriteLineをWriteとすると、改行なしで出力。
	}
}