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>
using namespace std;
#define ll long long
#define pb push_back
#define MOD 1000000007
#define pp pop_back
#define MAXN   100001
#define mp make_pair
#define endl '\n'
int main()
{
	string s;
	cin>>s;
	ll i;
	map<char,ll> m;
	for(i=0;i<(ll)s.size();i++)
	{
		m[s[i]]++;
	}
	ll x=s.size();
	ll ans=(x*(x-1))/2;
	char y='a';
	for(i=0;i<26;i++)
	{
		ll tem=m[y];
		ans-=(tem*(tem-1))/2;
		y++;
	}
	cout<<ans+1<<endl;
}