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
jaideeppyne:
20170705 15:03:38
Be careful with the output format. Got 1 WA for that. :( Use adhoc process.No need of stack. You can find a good method of how to approach the question in adhoc way without use of stacks on Quora . The explanation available is nice. 

vivace:
20170630 11:50:42
solvable using dp as well... O(n^2) 

viratian_070:
20170614 07:36:26
no stack needed.....think simple...simple adhoc problem 

da_201501181:
20170526 13:58:27
O(n) without Stack..!! :) 

iammangod96:
20170519 11:36:38
stack.size()/2 + cnt 

omprakash_40:
20170410 07:02:43
don't go after dynamic programming tag..


vivace:
20170401 01:29:59
read the question carefully @a_kk


a_kk:
20170324 16:28:35
what will be the answer for {{}


vladimira:
20170316 05:14:23
AC in 3rd go becouse smth wrong with input, reading by lines. 

nilabja16180:
20170226 16:38:03
Stack, AC in one GO!

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 