#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

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