import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static long MOD = 1000000007;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		final int K = sc.nextInt() - 1;
		
		final char[] inputs = sc.next().toCharArray();
		
		int[] trans = new int[N];
		Arrays.fill(trans, -1);
		
		LinkedList<Integer> open_stack = new LinkedList<Integer>();
		for(int index = 0; index < N; index++){
			if(inputs[index] == '('){
				open_stack.addFirst(index);
			}else{
				final int open_index = open_stack.removeFirst();
				
				trans[open_index] = index;
				trans[index] = open_index;
			}
		}
		
		System.out.println(trans[K] + 1);
	}
}