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 <string>
#include <utility>
#include <map>
#include <vector>
#include <functional>
#include <algorithm>

using namespace std;
using ll = long long;

#define reps(i,s,n) for(int (i) = (s) ;(i) < (n); (i)++)
#define rep(i,n) reps(i,0,n)

int main()
{
    string str;
    cin >> str;
    vector<ll> cnt(27,0);
    ll n = str.length();

    ll ans = (n * (n-1)) / 2 + 1;
    rep(i,n){
        cnt[str[i]-'a']++;
    }

    rep(i,26){
        //cout  <<cnt[i] << endl;
        ans -= (cnt[i] * (cnt[i] - 1)) / 2;
    }
    cout << ans << endl;

    return 0;
}