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)

/********************************************
 *Author*        :ZZZZone
 *Created Time*  : 六  8/26 21:19:20 2017
 *Ended  Time*  : 六  8/26 21:26:49 2017
 *********************************************/

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <stack>
using namespace std;
typedef pair<int, int> PII;
typedef long long LL;
typedef unsigned long long ULL;
const int MaxN = 2e5;
char s[MaxN + 5];
int sum[30][MaxN + 5];

int main()
{
    scanf("%s", s + 1);
    int len = strlen(s + 1);
    for(int i = 0; i < 26; i++){
        char c = i + 'a';
        for(int j = 1; j <= len; j++){
            if(s[j] == c) sum[i][j] = sum[i][j - 1] + 1;
            else sum[i][j] = sum[i][j - 1];
        }
    }
    LL ans = 0;
    for(int i = 1; i <= len; i++){
        ans = ans + (i - sum[s[i] - 'a'][i]);
    }
    printf("%lld\n", ans + 1);
    return 0;
}