#include<iostream>
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include<string>
#include<vector>
#include<cmath>
#include<stack>
#include<queue>
#include<sstream>
#include<algorithm>
#include<map>
#include<complex>
#include<ctime>
#include<set>
using namespace std;


#define li			long long int
#define rep(i,to)	for(li i=0;i<((li)(to));i++)
#define repp(i,start,to)	for(li i=(li)(start);i<((li)(to));i++)
#define pb			push_back
#define sz(v)		((li)(v).size())
#define bgn(v)		((v).begin())
#define eend(v)		((v).end())
#define allof(v)	(v).begin(), (v).end()
#define dodp(v,n)		memset(v,(li)n,sizeof(v))
#define bit(n)		(1ll<<(li)(n))
#define mp(a,b)		make_pair(a,b)
#define rin	rep(i,n)
#define EPS 1e-10
#define ETOL 1e-8
#define MOD 100000000
#define F first
#define S second
#define p2(a,b)		cout<<a<<"\t"<<b<<endl
#define p3(a,b,c)		cout<<a<<"\t"<<b<<"\t"<<c<<endl
#define NVAL 1000000000

typedef pair<li, li> PI;

li res[101010];

int main(){
	li n,k;
	cin>>n>>k;
	string s;
	cin>>s;

	stack<li> stk;
	rin{
		if(s[i]=='(')stk.push(i);
		else{
			res[stk.top()]=i;
			stk.pop();
		}
	}

	cout<<res[k-1]+1<<endl;

	return 0;
}