#if defined(__GNUG__) && !defined(__clang__)
#include <bits/stdc++.h>
#endif

#define inf(T) (numeric_limits<T>::min())
#define sup(T) (numeric_limits<T>::max())
#define rep(i,n) for (int i = 0; i < (n); i++)
#define asc(c) (c).begin(), (c).end()
#define desc(c) (c).rbegin(), (c).rend()
#define mp(...) make_pair(__VA_ARGS__)
#define mt(...) make_tuple(__VA_ARGS__)

using namespace std;

using ll = long long;
using ld = long double;

template <class Key>          using uset = unordered_set<Key>;
template <class Key, class T> using umap = unordered_map<Key, T>;

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, k;
  string s;
  cin >> n >> k >> s;
  k--;
  stack<int> st;
  rep(i,n) {
    if (s[i] == '(') {
      st.push(i);
    } else {
      int j = st.top();
      st.pop();
      if (i == k) {
        cout << j + 1 << endl;
        break;
      }
      if (j == k) {
        cout << i + 1 << endl;
        break;
      }
    }
  }

  return 0;
}