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;

namespace AGC019_B___Reverse_and_Compare
{
    class Program
    {
        static void Main(string[] args)
        {
            var A = Console.ReadLine();
            var alphabets = new int[26];
            for (int i = 0; i < A.Length; i++) alphabets[A[i] - 'a']++;
            var result = A.Length * (A.Length - 1) / 2 + 1;
            for (int i = 0; i < 26; i++) result -= alphabets[i] * (alphabets[i] - 1) / 2;

            Console.WriteLine(result);
        }
    }
}