using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Magatro
{
    static void Main()
    {
        string[] s = Console.ReadLine().Split(' ');
        int N = int.Parse(s[0]);
        int K = int.Parse(s[1])-1;
        string SS = Console.ReadLine();
        List<int> L = new List<int>();
        int[] c = new int[N];
        for(int i = 0; i < N; i++)
        {
            if (SS[i] == '(')
            {
                L.Add(i);
            }
            else
            {
                c[L[L.Count-1]] = i;
                c[i] = L[L.Count - 1];
                L.RemoveAt(L.Count - 1);
            }
        }
        Console.WriteLine(c[K]+1);
    }
}