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 <iostream>
#include <array>
#include <map>
#include <algorithm>
#include <cmath>
#include <vector>
#include <fstream>
#include <string>
#include <random>
#include <queue>
#include <iomanip>

using namespace std;

using ll = unsigned long long int;
using pii = pair<int, int>;

ll arr[100010] = {};

ll func(ll a) {
	return (a + 1)*a / 2;
}


int main() {

	string str;
	cin >> str;

	ll arr['z' - 'a' + 1] = {};

	for (int i = 0; i < str.size(); i++) {
		arr[str[i] - 'a']++;
	}

	ll ans = func(str.size()-1);

	for (int i = 'a'; i <= 'z'; i++) {
		ans -= func(arr[i - 'a']-1);
	}

	cout << ans+1 << endl;
}