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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define ll long long
#define rep(i,l,r)for(ll i=(l);i<(r);i++)
#define sum(n)((n)*((n)+1)/2)

char s[200010];
ll a[300];
int main(){
	scanf("%s",s);
	ll n=strlen(s);
	//#{(l,r)|l<=r}-#{(l,r)|l<=r s[l]==s[r]}+1
	
	ll ans=sum(n)+1;
	rep(i,0,n)a[s[i]]++;
	rep(i,0,300)ans-=sum(a[i]);
	
	printf("%lld\n",ans);
	return 0;
}