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>

const int N = 200010;
typedef long long ll;

char s[N];
int cnt[N];

int main(){
	scanf("%s", s);
	int n = strlen(s);
	for (int i = 0; i < n; ++ i){
		++ cnt[s[i]];
	}
	ll ans = 1ll * n * (n + 1) / 2 + 1;
	for (int i = 0; i < N; ++ i){
		ans -= 1ll * cnt[i] * (cnt[i] + 1) >> 1;
	}
	printf("%lld\n", ans);
	return 0;
}