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

int main() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  vector <int> stack;
  k--;
  for (int i = 0; i < n; i++) {
	  if (s[i] == '(') {
		  stack.push_back(i);
		}
	  else {
		  int j = stack.back();
		  stack.pop_back();
		  if (i == k) {
			  cout << j + 1 << endl;
			  break;
			} else if (j == k) {
			  cout << i + 1 << endl;
			  break;
			}
		}
	}
  return 0;
}