import java.util.Scanner;
import java.util.Stack;
public class No22 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int N = s.nextInt() , K = s.nextInt();
		s.nextLine();
		String St = s.nextLine();
		s.close();
		Stack<Integer> stack = new Stack<>();
		for(int i = 0;i < N;i++){
			if(St.charAt(i) == '('){
				stack.push(i);
			}else{
				if(i + 1 == K){
					System.out.println(stack.pop() + 1);
					break;
				}else if(stack.peek() + 1 == K){
					System.out.println(i + 1);
					break;
				}else{
					stack.pop();
				}
			}
		}

	}

}