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: Wrong Answer)

/*
    User ID: qcw
       Time: 2017-10-10 21:53:39
*/
#include<bits/stdc++.h>
using namespace std;

using namespace std;
int A[26],ans;
string s;
int main(){
    cin.tie(0),ios_base::sync_with_stdio(0);
    cin>>s;
    ans=s.size()*(s.size()-1)/2+1;
    for(auto& x:s)++A[x-'a'];
    for(int i{};i<26;++i)
        if(A[i])ans-=A[i]*(A[i]-1)/2;
    cout<<ans<<endl;
}