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)

#include<vector>
#include<iostream>
#include<string>
#include<algorithm>
#include<math.h>
#include<map>
#include<functional>
#include<queue>
#include<stack>
#include<string.h>
#include<list>
#define ll long long int
#define MOD 1000000007LL
using namespace std;

int main() {
    string s;
    cin>>s;
    int n=s.length();
    ll ans=(n*(n-1))/2;
    ll c[26]={};
    for(int i=0;i<n;i++){
        c[s[i]-'a']++;
    }
    for(int i=0;i<26;i++){
        if(c[i]>1){
            ans-=(c[i]*(c[i]-1))/2;
        }
    }
    cout<<ans+1<<endl;
}