#include <iostream>
using namespace std;

int main() {
	int n, k;
	cin >> n >> k;
	string line;
	cin >> line;
	int target = 0, current = 0;
	for (int i = 1; i < n; i++) {
		if (line[i] == '(') current++;
		else current--;
		if (i == k - 1) target = current;
	}
	for (int i = 0; i < n; i++) {
		if (i != k && current == target) {
			cout << i + 1 << endl;
			return 0;
		}
	}
}