#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define FOR(i, m, n) for(int i=(m); i<(n); ++i)
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define mp make_pair
#define pb push_back
#define dump(x) cerr << #x << " = " << (x) << endl;
using LL=long long;
using VI=vector<int>;
using VL=vector<long long>;
using VS=vector<string>;
using VVI=vector<vector<int>>;
using PII=pair<int, int>;
const int inf = (int)1e9;
const LL mod = (long long)1e9 + 7;
const double pi = acos(-1.0);
template<class T>void Sort(T & a) { sort(a.begin(), a.end()); }
template<class T>void ReSort(T& a) { sort(a.rbegin(), a.rend()); }
template<class T>void Reverse(T& a) { reverse(a.begin(), a.end()); }
template<class T>void Unique(T& a) { a.erase(unique(a.begin(), a.end()), a.end()); }
template<class T>auto Max(T a) { return *max_element(a.begin(), a.end()); }
template<class T>auto Min(T a) { return *min_element(a.begin(), a.end()); }
template<class T, class U>int Count(T a, U c) { return count(a.begin(), a.end(), c); }
template<class T, class U>U Sum(T a, U init = 0) { return accumulate(a.begin(), a.end(), init); }
template<class T>T Age(T a, T b) { return (a + b - 1) / b; }

int main() {
	int n, k; cin >> n >> k;
	string s; cin >> s;
	k--;
	int ans = 0;
	int d = s[k] == '(' ? 1 : -1;
	
	int cnt = 1, pos = k;
	while (cnt != 0) {
		pos += d;
		cnt += s[pos] == '(' ? d : -d;
	}
	cout << pos + 1 << endl;
}