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
2014-06-02 11:15:48 Ashwini
learnt a new thing. didnt know crucial can space optimisation prove at times :)
2014-05-24 11:52:16 Rishav Goyal
try to optimize N^2 with abit calculation -> AC with 7.!
2014-03-20 19:11:26 sai madan mohan reddy
getting SIGSEGV at 0.91 secs any help
2014-03-17 04:00:44 innovolt
another space optimization problem similar concept problem is LKS.....overall gud1 learnt a lot thanxx spoj
2014-01-20 10:13:47 Somesh Maurya™
any diff between aibohp and this prob???
2013-11-24 12:02:41 sandeepandey
TL is really unfair for Java Coders.Even space optimized solution with Fast IO getting TLE .
Should be relaxed a lil bit.
2013-05-28 06:25:17 Aradhya
nice problem :)
2013-05-13 11:05:35 nagato
its the same problem as AIBOHP ....
my code got accepted for AIBHOP but gives TLE for this
i dont understand wht to optimise
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