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>
#define int long long
const int inf=1145141919810893ll;
const int mod=1000000007ll;
const int hoge=1000000000ll;
const double pi=3.14159265358979324;
const int dd[]={0,-1,0,1,0};
using namespace std;
int n,m,h,w;
int p[26];
signed main(){
	int i,j,k;
	string s;
	cin>>s;
	int ans=1;
	for(auto x:s){
		for(i=0;i<26;i++)
			if(i!=x-'a')
				ans+=p[i];
		p[x-'a']++;
	}
	cout<<ans<<endl;
}