Competitions

# Stack Data Structure

# Insert Parentheses

Milhouse need to solve a school task by tomorrow and needs your help. Here is the task:

Given a string of parentheses, you must turn it into a well formed string by inserting as few parentheses as possible, at any position (you cannot delete or change any of the existing parentheses). A well-formed string of parentheses is defined by the following rules:

- The empty string is well formed.
- If
**s**is a well formed string,**(s)**is a well formed string. - If
**s**and**t**are well formed strings, their concatenation**st**is a well formed string.

As examples, "**(()())**", "" and "**(())()**" are well formed strings and "**())(**", "**()(**" and "**)**" are malformed strings.

#### Input

Given a string of parentheses, it contains between **1** and **50** characters, inclusive.

#### Output

Print the minimum number of parentheses that need to be inserted to make the input string into a well formed string.

Input example #1

(()(()

Output example #1

2