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
vengatesh15: 2017-01-28 10:34:07

Too strict Time limit..

prasoonbatham: 2017-01-26 14:06:15

Too strict time limit.
Same optimized code in java didn't get ac which in c++ did. :(

sas1905: 2016-12-21 19:52:57

space O(N^2) gets accepted with fast I/P in C++..

sriraj: 2016-10-28 23:51:20

Too strict time constraints :/ long long int : TLE, int : AC
Also space optimization required

amit_taps1997: 2016-10-28 15:53:05

Top Down Memoization AC

siddharth_0196: 2016-10-05 11:00:39

String : TLE
Char array : AC!
-__-

Min_25: 2016-08-05 02:10:30

Almost the same problem as AIBOHP.

shayan718: 2016-07-31 19:50:40

top 10 dp problems ;)

mkfeuhrer: 2016-07-22 07:35:59

space optimization-> O(3*n)->AC & top down lcs !!

SUBHAM SANGHAI: 2016-07-13 16:15:52

use scanf,printf instead of cin,cout and ios base

Last edit: 2016-07-13 16:16:08

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