using System;
using System.Text;
using System.Linq;
using System.IO;
namespace N
{
    class P
    {
        static void Main()
        {
            Console.SetIn(new StreamReader(Console.OpenStandardInput(10000)));
            string CSL = Console.ReadLine();
            int N = 0;
            int K = 0;
            for (int i = 0; i < CSL.Length; i++)
            {
                if (CSL[i] == ' ')
                {
                    N = int.Parse(CSL.Substring(0, i));
                    K = int.Parse(CSL.Substring(i));
                    break;
                }
            }

            char[] Text = Console.ReadLine().ToCharArray();

            int W_K = 0;
            int Ans = 0;
            char T = Text[K - 1];
            for (int i = 0; ; i++)
            {
                if (Text[i] == '(') W_K++;
                if (Text[i] == ')') W_K--;
                if (i == K - 1) break;
            }

            if(T=='(')
            {
                int W_S = W_K;
                for(int i=K-1; ;i++)
                {
                    if (Text[i] == '(') W_S++;
                    if (Text[i] == ')') W_S--;
                    if(W_S==W_K)
                    {
                        Ans = i+1;
                        break;
                    }
                }
            }
            else
            {
                int W_S = W_K;
                for (int i =0; ; i++)
                {
                    if (W_S == W_K)
                    {
                        Ans = i + 1;
                        break;
                    }
                    if (Text[i] == '(') W_S++;
                    if (Text[i] == ')') W_S--;
                   
                }
            }

            Console.WriteLine(Ans);
            Console.ReadKey();
        }
    }
}