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

int memo[10000];
int main() {
  int N, K;
  string s;
  cin >> N >> K >> s;
  stack<int> st;
  for (int i = 0; i < N; i++) {
    if (s[i] == '(') {
      st.push(i);
    }
    else {
      int x = st.top();
      st.pop();
      memo[x] = i;
      memo[i] = x;
    }
  }
  cout << memo[K-1] + 1 << endl;
  return 0;
}