using System;
using System.Collections;

public class Program {
	public static void Main() {
		string[] input = Console.ReadLine().Split(' ');
		int k = int.Parse(input[1]);
		string s = Console.ReadLine();
		Stack stack = new Stack();
		for (int i = 0; i < s.Length; i++) {
			if (s[i].Equals('(')) {
				stack.Push(i);
			} else if (s[i].Equals(')')) {
				int index = (int)stack.Pop() + 1;
				if (i + 1 == k) {
					Console.WriteLine(index);
				} else if (index == k) {
					Console.WriteLine(i + 1);
				}
			}
		}
	}
}