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 5.4.1) (judge verdict: Wrong Answer)

//#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

char buffer[200003] = { 0 };
char count[26] = { 0 };
int f(char c)
{
	return (c < 'a' || 'z' < c) ? 0 : 1;
}
int main(void)
{
	int i, cnt, answer;
	fgets(buffer, sizeof(buffer), stdin);
	for (cnt = 0; f(buffer[cnt]); ++cnt){
		count[buffer[cnt] - 'a']++;
	}
	answer = cnt * (cnt - 1) / 2 + 1;
	for (i = 0; i < 26; ++i){
		answer += -count[i] * (count[i] - 1) / 2;
	}
	printf("%d\n", answer);
	return 0;
}