#include <bits/stdc++.h>

using namespace std;

int main() {
	map<int, int> q;
	map<int, int> m;
	int N, K; cin >> N >> K; --K;
	string s; cin >> s;
	int nest = 0;
	for (int i = 0; i < N; ++i) {
		if (s[i] == '(') {
			q[nest] = i;
			++nest;
		}
		else {
			--nest;
			m[i] = q[nest];
			m[q[nest]] = i;
		}
	}
	cout << m[K]+1 << endl;
}