import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;


public class Main {
    public static void main(String[] args) throws IOException {

        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        String[] firstLine = reader.readLine().split(" ");
        int N = Integer.parseInt(firstLine[0]);
        int K = Integer.parseInt(firstLine[1]);

        String[] S = reader.readLine().split("");
        Stack<Parenthesis> stack = new Stack<>();
        for (int i = 0; i < N; i++) {

            if (S[i].equals("(")) {
                stack.add(new Parenthesis(S[i], i + 1));
            } else {
                Parenthesis parenthesis = stack.pop();
                if (i + 1 == K) {
                    System.out.println(parenthesis.index);
                    break;
                } else if (parenthesis.index == K) {
                    System.out.println(i + 1);
                    break;
                }
            }
        }
    }
}

class Parenthesis {
    String value;
    int index;

    Parenthesis(String value, int index) {
        this.value = value;
        this.index = index;
    }

    @Override
    public String toString() {
        return "Parenthesis{" +
                "value='" + value + '\'' +
                ", index=" + index +
                '}';
    }
}