#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>
//#include<bits/stdc++.h>


using namespace std;

int main(){


	int a,b;
	cin>>a>>b;
	string p;
	b--;
	cin>>p;
	int t=0;
	if(p[b]=='('){
		t=-1;
		for(int i=b+1;i<p.size();i++){
			if(p[i]=='(')t--;
			else t++;
			if(t==0){
				cout<<i+1<<endl;
				return 0;
			}
		}
	}
	t=1;
	for(int i=b-1;i>=0;i--){
			if(p[i]=='(')t--;
			else t++;
			if(t==0){
				cout<<i+1<<endl;
				return 0;
			}
		}

	
	return 0;
}