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

public class Main {
	public static void main(String[] args) {
		BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));

		try {
			String[] str = buff.readLine().split(" ");
			int N = Integer.parseInt(str[0]);
			int K = Integer.parseInt(str[1]) - 1;
			String s = buff.readLine();
			StringBuilder line = new StringBuilder(s);

			boolean flag = true;
			int ans = -1;
			for (int i = 0; i < N && flag; ++i) {
				if (line.charAt(i) == '(') {
					for (int j = i + 1; j < N; ++j) {
						if (line.charAt(j) == '(') {
							break;
						}
						if (line.charAt(j) == ')') {

							if (i == K) {
								ans = j;
								flag = false;
							} else if (j == K) {
								ans = i;
								flag = false;
							} else {
								line.setCharAt(i, ' ');
								line.setCharAt(j, ' ');
								i = -1;
							}
							break;
						}

					}

				}
			}
			System.out.println(ans + 1);

		} catch (NumberFormatException e) {

		} catch (IOException e) {

		}
	}
}