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)

#include <bits/stdc++.h>

using namespace std;

#define N 200000

string str;
long long c[256];
int n;

long long nc2(long long n){
	return (n * (n - 1)) / 2;
}

int main(){
	long long ans;
	int i;

	ios::sync_with_stdio(false);

	cin >> str;
	n = (int)str.size();
	ans = nc2(n) + 1;

	for (i = 0; i < n; i++){
		c[(int)str[i]]++;
	}

	for (i = 'a'; i <= 'z'; i++){
		ans -= nc2(c[i]);
	}

	cout << ans << endl;

	return 0;
}