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

int main() {
  int N, K;
  string S;
  cin >> N >> K >> S;
  K--;
  vector V(N, 0);
  stack<int> ST;
  for (int i = 0; i < N; i++) {
    if (S.at(i) == '(') ST.push(i);
    else {
      int top = ST.top();
      ST.pop();
      V.at(i) = top;
      V.at(top) = i;
    }
  }
  cout << V.at(K) + 1 << "\n";
}