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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <algorithm>
#include <math.h>
#include <string>
using namespace std;

int main() {
  string a;
  int n, total;
  int c[26];
  for(int k = 0; k<26; k++){
    c[k] = 0;
  }
  
  cin >> a;
  n = a.length();
  for(int i = 0; i<n; i++){
    c[a[i] - 'a']++;
  }
  total = n*(n-1)/2 +1;
  for(int j = 0; j<26; j++){
    total -= c[j]*(c[j]-1)/2;
  }
  cout << total << endl;
  return 0;
}