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;
		int K2 = K - 1;
		String[] str = new String[N];
		for (int i = 0; i < N; i++) {
			str[i] = S.substring(i, i + 1);
		}
		if (str[K2].equals("(")) {
			while (true) {
				if (c == 0) {
					System.out.println(K2 + 1);
					break;
				}else if (str[K2 + 1].equals("(")) {
				c++;
				K2++;
			} else if (str[K2 + 1].equals(")")) {
				c--;
				K2++;
			}
			}
		}else if(str[K2].equals(")")){
			while(true){
				if(c == 0){
					System.out.println(K2 + 1);
					break;
				}else if(str[K2 - 1].equals(")")){
					c++;
					K2--;
				}else if(str[K2 - 1].equals("(")){
					c--;
					K2--;
				}
			}
		}
	}
}