import java.util.*;
 

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		String s = sc.next();
		Stack<Integer> a = new Stack<Integer>();
		for(int i=0;i<n;i++){
			char rr=s.charAt(i);
			if(rr=='('){
				a.add(i+1);
			}else{
				if(i+1==m){
					System.out.println(a.pop());
					return;
				}
				if(a.pop()==m){
					System.out.println(i+1);
					return;
				}
			}
		}
	}
}