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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Scanner;
import java.util.TreeSet;

public class Main {

	public static void main(String[] args) {
		new Main().solve();
	}
	
	void solve(){
		Scanner sc=new Scanner(System.in);
		String s=sc.next();
		int n=s.length();
		int[]alph=new int[26];
		ArrayList<Integer>[] alphId=new ArrayList[26];
		for(int i=0;i<26;i++) {
			alphId[i]=new ArrayList<Integer>();
		}
		for(int i=0;i<n;i++) {
			alph[s.charAt(i)-'a']++;
			alphId[s.charAt(i)-'a'].add(i);
		}
		
		long ans=n*(n-1)/2+1;
		for(int k=0;k<26;k++) {
			if(alph[k]>1) {
				for(int i=0;i<alphId[k].size();i++) {
					for(int j=i+1;j<alphId[k].size();j++) {
						if(alphId[k].get(j)-alphId[k].get(i)<=2)ans--;
						else {
							ans--;
						}
					}
				}
			}
		}
		System.out.println(ans);
	}
}