using System;
using System.Collections.Generic;

namespace No22_1{
    public class Program{
        public static void Main(string[] args){
            var sr = new StreamReader();
            //---------------------------------
            var n = sr.Next<int>();
            var k = sr.Next<int>();
            var s = sr.Next<string>();

            var stk = new Stack<int>();
            var result = new int[n];
            for(var i = 0; i < n; i++){
                if(s[i] == '(') stk.Push(i);
                else{
                    var p = stk.Pop();
                    result[p] = i;
                    result[i] = p;
                }
            }

            Console.WriteLine(result[k - 1] + 1);
            //---------------------------------
        }
    }

    public class StreamReader{
        private readonly char[] _c = {' '};
        private int _index = -1;
        private string[] _input = new string[0];

        public T Next<T>(){
            if(_index == _input.Length - 1){
                _index = -1;
                while(true){
                    var rl = Console.ReadLine();
                    if(rl == null){
                        if(typeof(T).IsClass) return default(T);
                        return (T)typeof(T).GetField("MinValue").GetValue(null);
                    }
                    if(rl != ""){
                        _input = rl.Split(_c, StringSplitOptions.RemoveEmptyEntries);
                        break;
                    }
                }
            }
            return (T)Convert.ChangeType(_input[++_index], typeof(T), System.Globalization.CultureInfo.InvariantCulture);
        }

        public T[] Next<T>(int x){
            var result = new T[x];
            for(var i = 0; i < x; ++i){
                result[i] = Next<T>();
            }
            return result;
        }

        public T[,] Next<T>(int y, int x){
            var result = new T[y, x];
            for(var i = 0; i < y; ++i){
                for(var j = 0; j < x; ++j){
                    result[i, j] = Next<T>();
                }
            }
            return result;
        }
    }
}