#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>
#include <time.h>
using namespace std;
//#define int long long
#define rep(i,s,n) for(int i = s;i<n;i++)
#define repe(i,s,n) for(int i = s;i<=n;i++)
#define rrep(i,s,n) for(int i = (n)-1;i>=(s);i--)
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define fi first
#define se second
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))
#define l1 list[index]
#define l2 list[index - 1]
#define l3 list[index + 1]
#define iif(i,j) ((i<0 && j<0) || (i>0 && j>0)) ? true : false 
typedef long long ll;
typedef pair<int, int>pint;
typedef vector<int>vint;
typedef vector<pint>vpint;
typedef pair<pint, int> P1;
typedef pair<int, pint> P2;
typedef pair<pint, pint> PP;
static const ll maxLL = (ll)1 << 62;
const ll MOD = 1000000007;
const ll INF = 1e18;
int ca[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };



signed main() {
	string s;
	int n, k, cnt = 0;
	vector<int>list(10005, 99999999);

	cin >> n >> k >> s;

	for (int i = 1; i <= s.length(); i++) {
		if (s[i-1] == '(') {
			cnt++;
		}
		else {
			/*if (i - 2 >= 0 && s[i - 2] == '(') {
				cnt--;
			}
			else {
				cnt--;
			}*/

			cnt--;
		}

		list[i] = cnt;
	}


	if (s[k - 1] == '(') {
		for (int i = k; i <= s.length(); i++) {
			if (list[i] == list[k] - 1 && s[i - 1] == ')' ) {
				cout << i << endl;
				break;
			}
		}
	}
	else {

		/*for (int i = 1; i <= s.length(); i++) {
			if (list[i] == list[k] + 1 && s[i - 1] == '(' ) {
				cout << i << endl;
				break;
			}
		}*/

		for (int i = k - 1; i >= 0; i-- ) {
			if (list[i] == list[k] + 1 && s[i - 1] == '(') {
				cout << i << endl;
				break;
			}
		}

	}





	getchar();
	getchar();
	return 0;
}