Contest: Task: Related: TaskA TaskC

Score : $500$ points

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?

- $1 \leq |A| \leq 200,000$
- $A$ consists of lowercase English letters.

Input is given from Standard Input in the following format:

$A$

Print the number of different strings you can obtain by reversing any substring in $A$ at most once.

aatt

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 $A[1..3]$).

xxxxxxxxxx

1

Whatever substring you reverse, you'll always get `xxxxxxxxxx`

.

abracadabra

44