ANARC09A  Seinfeld
I’m out of stories. For years I’ve been writing stories, some rather silly, just to make simple problems look difficult and complex problems look easy. But, alas, not for this one.
You’re given a non empty string made in its entirety from opening and closing braces. Your task is to find the minimum number of “operations” needed to make the string stable. The definition for being stable is as follows:
 An empty string is stable.
 If S is stable, then {S} is also stable.
 If S and T are both stable, then ST (the concatenation of the two) is also stable.
All of these strings are stable: {}, {}{}, and {{}{}}; But none of these: }{, {{}{, nor {}{.
The only operation allowed on the string is to replace an opening brace with a closing brace, or visaversa.
Input
Your program will be tested on one or more data sets. Each data set is described on a single line. The line is a nonempty string of opening and closing braces and nothing else. No string has more than 2000 braces. All sequences are of even length.
The last line of the input is made of one or more ’’ (minus signs.)
Output
For each test case, print the following line:
k. N
Where k is the test case number (starting at one,) and N is the minimum number of operations needed to convert the given string into a balanced one.
Example
Input: }{
{}{}{}
{{{}

Output: 1. 2
2. 0
3. 1
hide comments
KUMAR ABHISHEK:
20150521 11:21:15
The string to be checked should always be even ? 

SangKuan:
20150519 14:09:36
notice there is a '\r' at the end of every line,it cost me one time 

:.Mohib.::
20150519 04:38:45
O(n) simple :) Last edit: 20150519 04:39:08 

who cares:
20150504 05:41:05
and the happiest moment when your solution got accepted in first attempt with o(n) ;) 

Aadil Ahmad:
20150407 19:06:01
My 50th :) :) :) 

Ayman Mostafa:
20150325 13:06:59
{}{{{}}} is this stable? 

xxbloodysantaxx:
20150322 11:24:53
That was a total fluke.. I did it by stacks not even thinking what I did (going by intuitions) it went AC .. Now I need to prove the correctness of my algorithm 

Daniel Carvalho:
20150303 20:08:33
@Mahesh Kohli, yes, it is.


Mahesh Kohli:
20150218 14:48:29
sir,


Petar Jesic:
20150206 13:27:00
This is one of those problems where the input format gets you into more trouble than the problem itself. 
Added by:  Mohammad Kotb 
Date:  20091128 
Time limit:  3.236s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 BASH JSRHINO 
Resource:  http://www.icpcanarc.org 