package yukicoder;

import java.util.Scanner;

public class No22 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int K = sc.nextInt();
		sc.nextLine();
		String S = sc.nextLine();
		sc.close();
		int c = 1;
		String str = S.substring(K - 1, K);
		if (str.equals("(")) {
			while (true) {
				str = S.substring(K, K + 1);
				if (c == 0) {
					System.out.println(K);
					break;
				} else if (str.equals("(")) {
					c++;
					K++;
				} else if (str.equals(")")) {
					c--;
					K++;
				}
			}
		} else if (str.equals(")")) {
			int K2 = K - 1;
			while (true) {
				if(K2==0){
				str = S.substring(K2,K2 + 1);
				System.out.println(1);
				break;
				}
				if (c == 0) {
					System.out.println(K2 + 1);
					break;
				}else if (str.equals(")")) {
					c++;
					K2--;
				} else if (str.equals("(")) {
					c--;
					K2--;
				}
			}
		}
	}
}