#include <bits/stdc++.h>
using namespace std;

int main() {
  int N, K;
  string S;
  cin >> N >> K >> S;
  K--;
  vector<int> V(N);
  set<int> SE;
  for (int i = 0, id = 0; i < N; i++) {
    if (S.at(i) == '(') V.at(i) = id++;
    else {
      int tmp = id - 1;
      while (SE.count(tmp)) tmp--;
      V.at(i) = tmp;
      SE.insert(tmp);
    }
  }
  int tmp = V.at(K);
  for (int i = 0; i < N; i++) {
    if (i == K) continue;
    if (V.at(i) == tmp) return cout << i + 1 << "\n", 0;
  }
}