#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, m;
	string s;
	cin >> n >> m;
	cin >> s;
	int counter = 0;
	if (s[m - 1] == '(') {
		for (int i = m; i < s.length(); ++i) {
			if (s[i] == '(') {
				counter++;
			} else if (counter == 0) {
				cout << i + 1 << endl;
				return 0;
			} else {
				counter--;
			}
		}
	} else {
		for (int i = m-2; i >= 0; --i) {
			if (s[i] == ')') {
				counter++;
			} else if (counter == 0) {
				cout << i + 1  << endl;
				return 0;
			} else {
				counter--;
			}
		}
	}
}