#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	int n,k;
	cin>>n>>k;
	vector<int> st;
	string s;
	cin>>s;
	k--;
	int ans;
	rep(i,n){
		if(s[i]=='('){
			st.push_back(i);
		}else{
			int a=st.back();
			st.pop_back();
			if(i==k)ans=a;
			else if(a==k)ans=i;
		}
	}
	cout<<ans+1<<endl;
	return 0;
}