using System;
using System.Linq;
using System.Collections.Generic;

namespace Algorithm
{
    class Program
    {
        static void Main(string[] args)
        {
            var l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int N = l[0], K = l[1];
            var S = Console.ReadLine();

            var stack = new Stack<int>();
            var right = S[K - 1] == '(' ? true : false;
            var ans = 0;
            var count = 0;
            for (var i = 0; i < S.Length; i++)
            {
                if (S[i] == '(')
                    stack.Push(i + 1);
                else
                    count = stack.Pop();

                if (right && count == K)
                {
                    ans = i + 1;
                    break;
                }

                if (!right && i + 1 == K)
                {
                    ans = count;
                    break;
                }
            }

            Console.WriteLine(ans);
        }
    }
}