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++14 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<iostream>
#include<vector>
#include<queue>
#include<deque>
#include<stack>
#include<cstdio>
#include<utility>
#include<algorithm>
using std::cout;
using std::cin;
using std::endl;

int main(void){
    std::string s;
    cin >> s;
    long long answer = s.size() * (s.size() - 1) / 2;
    //cout << "first answer:" << answer << endl;

    for (char i = 'a'; i <= 'z'; i++)
    {
        int count = 0;
        for (int j = 0; j < s.size();j++){
            if(s[j]==i){
                count++;
            }
        }
            answer -= count * (count - 1) / 2;
    }
    cout << answer+1 << endl;

    return 0;
}