#include <iostream>
#include <string>
#include <stack>

int left(const std::string &express, const int &k) {
	std::stack<int> stack;
	for (auto i = express.size() - 1; i > k; --i) {
		switch (express[i]) {
		case ')':
			stack.push(i);
			break;
		case '(':
			stack.pop();
		}
	}
	return stack.top() + 1;
}
int right(const std::string &express, const int &k) {
	std::stack<int> stack;
	for (auto i = 0; i < k; ++i) {
		switch (express[i]) {
		case '(':
			stack.push(i);
			break;
		case ')':
			stack.pop();
		}
	}
	return stack.top() + 1;
}
int main() {
	int n, k;
	std::string expression;
	std::cin >> n >> k >> expression;
	switch (expression[--k]) {
	case '(':
		std::cout << left(expression, k) << std::endl;
		break;
	case ')':
		std::cout << right(expression, k) << std::endl;
	}
	return 0;
}