IOIPALIN - Palindrome 2000

A palindrome is a symmetrical string, that is, a string read identically from left to right as well as from right to left. You are to write a program which, given a string, determines the minimal number of characters to be inserted into the string in order to obtain a palindrome. As an example, by inserting 2 characters, the string "Ab3bd" can be transformed into a palindrome ("dAb3bAd" or "Adb3bdA"). However, inserting fewer than 2 characters does not produce a palindrome.

Input

The first line contains one integer: the length of the input string N, 3 ≤ N ≤ 5000. The second line contains one string with length N. The string is formed from uppercase letters from ‘A’ to ‘Z’, lowercase letters from ‘a’ to ‘z’ and digits from ‘0’ to ‘9’. Uppercase and lowercase letters are to be considered distinct.

Output

The first line contains one integer, which is the desired minimal number.

Example

Input:
5
Ab3bd

Output:
2

Added by:Gareev
Date:2010-08-16
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS OBJC PERL6 VB.NET
Resource:IOI 2000, Day 1

hide comments
2015-12-18 23:36:49 sneh sajal
try to optimize space in linear :)
2015-12-18 18:42:37 janina
O(n^2) space O(n^2) time and scanf,printf will give you AC.
2015-12-09 19:46:28
linear space is the key to AC
2015-10-23 07:00:25 LEMONICE
I am not able to submit! It says Error,Wrong problem code!
2015-10-03 07:52:48 Shubham Garg
Use faster method for string input. No space optimization is required.But space optimization does give lower time.

Last edit: 2015-10-03 08:07:29
2015-09-25 20:27:54 ashish
no space optimisation is required.
use faster Input output method.
2015-07-28 17:00:58 Mauro Persano
No spoilers, please!
2015-07-03 19:16:21 no name
just removed function call overhead, without doing any space or any optimization at all. AC :O
there is just some problem with the time limit, otherwise a simple problem

Last edit: 2015-07-03 19:17:42
2015-06-14 10:01:26 Carlos Vinícios
I got AC without any space optimization.
2015-06-09 19:04:57 Ankit
nice que ,AC in one go:)

Last edit: 2015-06-09 19:05:37
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