#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<vector>
#include<list>
#include<algorithm>
#include<utility>
#include<complex>
#include<functional>
using namespace std;


int main(void){
	int N, K;
	int mv = 1;
	string s;
	cin >> N >> K >> s;
	K--;
	if (s[K] == ')')mv=-1;
	int cnt = 0;
	K += mv;
	for (int i = K; cnt !=1; i+=mv){
		if (s[i] == s[K])cnt--;
		else cnt++;
		if (cnt == 1)cout << i + 1 << endl;
	}
	return 0;
}