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 fir first
#define sec second
using namespace std;
typedef long long LL;
typedef unsigned long long u64;

template <typename T> inline bool cmin(T & a, const T & b) { return a > b ? a = b, 1 : 0;}
template <typename T> inline bool cmax(T & a, const T & b) { return a < b ? a = b, 1 : 0;}
int inp() {
	int x = 0, f = 1;char ch;
	for(ch = getchar(); !isdigit(ch); ch = getchar())
		if(ch == '-') f = -1;
	for(; isdigit(ch); x = x * 10 + ch - '0', ch = getchar());
	return x * f;
}

const int MaxN = 201234;
char a[MaxN]; int n;
int b[MaxN];
int main() {
	int i;
	scanf("%s", a + 1); n = strlen(a + 1); 
	LL ans = (LL) n * (n + 1) / 2;
	
	for(i = 1; i <= n; i++) 
		b[a[i] - 'a']++;
	for(i = 0; i < 26; i++) ans -= (LL) b[i] * (b[i] + 1)/2;
	cout << ans + 1;
	return 0;
}