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: Accepted)

#include <stdio.h>
#include <stdlib.h>

#define int long long
#define max_size (int)(2 * 1e5 + 1)

int main(){
	int i, j, N, ans = 1;
	char *A = (char *)malloc(sizeof(char) * max_size);
	scanf("%s", A);
	for(i = 0; A[i] != '\0'; i++){}
	N = i;
	int **sum = (int **)malloc(sizeof(int *) * N);
	for(i = 0; i < N; i++){
		sum[i] = (int *)malloc(sizeof(int) * 26);
		for(j = 0; j < 26; j++){
			sum[i][j] = 0;
		}
	}
	for(i = 0; i < N; i++){
		sum[i][(int)A[i] - (int)'a']++;
	}
	for(i = 1; i < N; i++){
		for(j = 0; j < 26; j++){
			sum[i][j] += sum[i - 1][j];
		}
	}
	for(i = N - 1; i >= 0; i--){
		ans += i - sum[i][(int)A[i] - (int)'a'] + 1;
	}
	printf("%lld\n", ans);
	return 0;
}