#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<cstdio>
#include<sstream>
#include<iomanip>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-8;
const int inf=1<<30;
int main(){
	int n,m;
	cin>>n>>m;
	string s;
	cin>>s;
	m--;
	bool h=false;
	if(s[m]==')'){
		h=true;
		reverse(all(s));
		m=n-1-m;
		rep(i,s.size())if(s[i]=='(')s[i]=')';
		else s[i]='(';
	}
	int sum=-1;
	int t=0;
	rep(i,n){
		if(i==m)sum=t;
		if(s[i]=='(')t++;
		else t--;
		if(sum==t){
			i++;
			if(h)i=n-i+1;
			cout<<i<<endl;
			return 0;
		}		
	}
}