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 <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<(n); ++i)
#define rep1(i,n) for(int i=1; i<=(n); ++i)
#define repi(i,a,b) for(int i=a; i<=(b); ++i)
#define ALL(obj) (obj).begin(), (obj).end()
#define RALL(obj) (obj).rbegin(), (obj).rend()
#define pb push_back
#define mp make_pair
#define sz(v) (int)v.size()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
using ll = long long;
using namespace std;
typedef pair<int,int> P;
struct aaa{aaa(){ cin.tie(0); ios::sync_with_stdio(0); cout<<fixed<<setprecision(20);};}aaaaaaa;
int MOD = 1e9 + 7;
int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return (a*b)/gcd(a,b);}
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

string A;
int main(){
    cin >> A;
    map<char,ll> box;
    ll total = (sz(A)-1)*sz(A)/2;
    rep(i,sz(A)) box[A[i]]++;
    repi(i,'a','z') total -= box[i]*(box[i]-1)/2;
    cout << total+1 << endl;
}