#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <string>

using namespace std;

int main() {
  int n, k;
  cin >> n >> k;
  string str;
  cin >> str;
  int memo[n];
  stack <int> st;
  for (int i = 0; i < str.size(); i++) {
    if (str[i] == '(') {
      memo[i] = i+1;
      st.push(i);
    }
    if (str[i] == ')') {
      memo[i] = st.top()+1;
      st.pop();
    }
  }
  for (int i = 0; i < n; i++) {
    if (str[i] != str[k-1] && memo[i] == k) {
      cout << i+1 << endl;
      return 0;
    }else if (memo[k-1] == memo[i] && str[i] != str[k-1]) {
      cout << i+1 << endl;
      return 0;
    }
  }
}