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<string>
#include<vector>
#include<algorithm>
#include<queue>

using namespace std;

int main(){
    string A;
    cin>>A;

	int count=0;
	long long dual=0;
	char rt;
	long long chp=0;
	long long pena=1;
	vector <bool>z(26,false);
	sort(A.begin(),A.end());
	rt=A[0];
	z[(int)A[0]-'a']=true;
	for(int i=1 ;i<A.size() ; i++){
		chp+=i;
		z[(int)A[i]-'a']=true;
		if(rt==A[i]){
			dual+=pena;
			pena+=1;
		}
		else{
			rt=A[i];
			pena=1;
		}
	}
	for(int i=0 ; i<26 ; i++){
		if(z[i]==true)count+=1;
	}

    cout<<1+chp-dual<<endl;
    
    return 0;
}