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
rohit9934: 2017-11-05 13:18:07


problema clásico de DP

shikhars387: 2017-10-11 19:09:24

Easy DP :)
Spoiler comments.

Last edit: 2017-10-11 19:10:05
raghav_chawla7: 2017-09-26 11:51:39

O(N*N) time and O(N*N) space accepted in 1 go

nikmul19: 2017-09-24 06:56:10

O(n^2) time complexity not passing

mastik5h_1998: 2017-09-20 09:22:12

don't write anything extra and O(n*n) space complexity gives AC :)

aman_9899: 2017-06-27 21:10:58

recursion..!!!

shubham8_: 2017-06-23 23:15:57

Just use scanf printf without space optimization it also passes

up79: 2017-06-07 21:31:21

who says time limit is strict ?
similar with lcs . O(n^2) dp is passing , but do take care of space complexity :)
easy one . :)

da_201501181: 2017-06-06 07:06:46

NEEDS Space Optimisation..!!

cake_is_a_lie: 2017-03-04 00:13:28

cin/cout; string; 0.17-0.19s AC

Quit blaming the frameworks and optimize your implementation!


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