1023C · Bracket Subsequence

Problem: A bracket sequence is a string containing only characters "(" and ")". A regular bracket sequence is a bracket sequence that can be transformed into a correct arithmetic expression by inserting characters "1" and "+" between the original characters of the sequence. For example, bracket sequences "()()" and "(())" are regular (the resulting expressions are: "(1)+(1)" and "((1+1)+1)"), and ")(", "(" and ")" are not.

Subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.

You are given a regular bracket sequence $s$ and an integer number $k$. Your task is to find a regular bracket sequence of length exactly $k$ such that it is also a subsequence of $s$.

It is guaranteed that such sequence always exists.

Input Format: The first line contains two integers $n$ and $k$ ($2 \le k \le n \le 2 \cdot 10^5$, both $n$ and $k$ are even) — the length of $s$ and the length of the sequence you are asked to find.

The second line is a string $s$ — regular bracket sequence of length $n$.

Output Format: Print a single string — a regular bracket sequence of length exactly $k$ such that it is also a subsequence of $s$.

It is guaranteed that such sequence always exists.