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 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <vector>
#include <deque>
#include <math.h>
#include <set>
#include <iomanip>
#include <time.h>
#include <list>
#include <stdio.h>
#include <queue>
#include <map>
#include <algorithm>
#include <assert.h>
#include <memory.h>

#define mk make_pair
#define sc second
#define fr first
#define pb emplace_back
#define all(s) s.begin(), s.end()
#define sz(s) ( (int)s.size() )
#define int long long

using namespace std;

string s;

int n, ans;

map <char, int> mp;

main ()
{
//    freopen("contest.in", "r", stdin);
//    freopen("contest.out", "w", stdout);
    cin >> s;
    n = s.size();
    s = ' ' + s;
    for (int i = 1; i <= n; i++)
    {
        mp[ s[i] ]++;
    }
    for (int i = 'a';  i <= 'z'; i++)
    {
        ans += mp[i] * (mp[i] - 1) >> 1;
    }
    cout << n * (n - 1) / 2 - ans + 1   ;
}