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: Wrong Answer)

#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <limits.h>
#include <math.h>
#include <queue>
#include <set>
#include <stdlib.h>
#include <string>
#include <vector>
#include <cstdio>
#define ll long long
#define rep2(i,a,b) for(int i=a;i<=b;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define rep3(i,a,b) for(int i=a;i>=b;i--)
#define REP(e,v) for(auto e:v)
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pq priority_queue<int>
#define pqg priority_queue<int,vector<int>,greater<int>()>
#define pb push_back
#define vec vector<int>
#define vecll vector<ll>
#define bs binary_search
#define All(c) (c).begin(),(c).end()
#define mp make_pair
using namespace std;
int in(){int x;scanf("%d",&x);return x;}
string stin(){string s;cin>>s;return s;}
ll lin(){ll x;scanf("%lld",&x);return x;}
int main(){
    string s=stin();
    ll n=s.length();
    vec a(26);
    rep(i,n)a[s[i]-'a']++;
    ll ans=n*(n-1)/2+1;
    rep(i,26)ans-=a[i]*(a[i]-1)/2;
    cout<<ans<<endl;
}