#include <iostream>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
	int n, k;
	cin >> n >> k;
	cin.setf(ios_base::skipws);
	string s;
	cin >> s;
	int position = k;
	int direction = ((s[position - 1] == '(') ? 1 : -1);
	int depth = direction;
	do {
		position += direction;
		depth += ((s[position - 1] == '(') ? 1 : -1);
	} while (depth != 0);

	cout << position << endl;

	return 0;
}