#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <functional>
#include <set>
#include <numeric>
#include <stack>
#include <utility>
//#include "util.h"

using namespace std;
typedef long long lint;
typedef pair<lint, lint> Pii;

int main()
{
	int N, K;
	string S;
	cin >> N >> K >> S;
	stack<int> st;
	for (int i = 0; i < N; i++) {
		if (S[i] == '(') {
			st.push(i + 1);
		}
		else {
			int l = st.top(), r = i + 1;
			if (l == K || r == K) {
				cout << (l == K ? r : l) << endl;
				break;
			}
			st.pop();
		}
	}

	return 0;
}