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

hide comments
Aradhya: 2013-05-28 06:25:17

nice problem :)

nagato: 2013-05-13 11:05:35

its the same problem as AIBOHP ....
my code got accepted for AIBHOP but gives TLE for this
i dont understand wht to optimise

Michal Polivka: 2013-03-08 16:41:40

Time limit is wrong for this problem...

符号器: 2012-12-22 20:13:44

ny 1 got AC by O(N^2)???????????

Rishi Mukherje: 2012-07-31 12:01:50

Solving AIBOHP took a day. Solving this one took 5mins. :D

Rajkiran Rajkumar: 2012-04-07 18:08:52

Can you please check my code? It fails after 10 test files :( Same logic as AIBOHP but optimised.

Santiago Palacio: 2011-05-30 02:23:26

Does the Case matters (a != A) ?

Last edit: 2011-05-30 02:23:47
pankaj: 2011-05-27 07:46:28

reduction of problem is needed.


Added by:Gareev
Date:2010-08-16
Time limit:0.158s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS OBJC PERL6 VB.NET
Resource:IOI 2000, Day 1