papplesort

papplesort

Problem Statement

You are given a string S consisting of lowercase English letters. Determine whether we can turn S into a palindrome by repeating the operation of swapping two adjacent characters. If it is possible, find the minimum required number of operations.

Constraints

  • 1 ≤ |S| ≤ 2 × 105
  • S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If we cannot turn S into a palindrome, print -1. Otherwise, print the minimum required number of operations.

Sample Input 1

eel

Sample Output 1

1

We can turn S into a palindrome by the following operation:

  • Swap the 2-nd and 3-rd characters. S is now ele.

Sample Input 2

ataatmma

Sample Output 2

4

We can turn S into a palindrome by the following operation:

  • Swap the 5-th and 6-th characters. S is now ataamtma.
  • Swap the 4-th and 5-th characters. S is now atamatma.
  • Swap the 3-rd and 4-th characters. S is now atmaatma.
  • Swap the 2-nd and 3-rd characters. S is now amtaatma.

Sample Input 3

snuke

Sample Output 3

-1

We cannot turn S into a palindrome.


Submitting .cpp to 'papplesort'


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Compile Errors


							
Time Limit: 2 Seconds
Memory Limit: 1024MB
No. of ACs: 2
Your best score: 0
Source: Dunjudge Archive

Subtask Score
1 100
2 0