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
mohsin mohammad: 2014-08-11 19:09:21

happy DP :) AC!

Sachin Malhotra: 2014-07-27 23:53:05

ummm.. In Love with DP :) :)..

Sachin Malhotra: 2014-07-27 22:30:22

Bottom up also giving TLE :(

Last edit: 2014-07-27 22:58:12
Mohamed Essam: 2014-06-09 11:44:58

Changed variable names, got AC -_-

Ashwini: 2014-06-02 11:15:48

learnt a new thing. didnt know crucial can space optimisation prove at times :)

Rishav Goyal: 2014-05-24 11:52:16

try to optimize N^2 with abit calculation -> AC with 7.!

sai madan mohan reddy: 2014-03-20 19:11:26

getting SIGSEGV at 0.91 secs any help

innovolt: 2014-03-17 04:00:44

another space optimization problem similar concept problem is LKS.....overall gud1 learnt a lot thanxx spoj

Somesh Maurya™: 2014-01-20 10:13:47

any diff between aibohp and this prob???

sandeepandey: 2013-11-24 12:02:41

TL is really unfair for Java Coders.Even space optimized solution with Fast IO getting TLE .
Should be relaxed a lil bit.


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