/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        // your code goes here
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] lines = br.readLine().split(" ");
        int n = Integer.parseInt(lines[0]);
        int k = Integer.parseInt(lines[1])-1;
        String line = br.readLine();
        
        Deque<Integer> deque = new ArrayDeque<Integer>();
        for(int i=0;i<n;i++){
            char c = line.charAt(i);
            if(c == '('){
                deque.addFirst(i);
            }else if(c == ')'){
                int t = deque.removeFirst();
                if(t == k){
                    System.out.println(i+1);
                    break;
                }else if(i == k){
                    System.out.println(t+1);
                    break;
                }
            }
        }
    }
}