#include<iostream>
#include<string>


using namespace std;

int main(){
	int N,K;
	string S;
	int turn;

	cin >> N >> K;
	cin >> S;


	if(S[K-1] == '(')
		turn = 1;
	else
		turn = -1;

	int flag = 1;

	while(flag != 0){
		K = K+turn;
		if(S[K-1] == '(')
			flag += turn;
		else
			flag -= turn;

	}
	cout << K << endl;
	return 0;
}