#include <iostream>
#include <vector>
#include <string>
using namespace std;

int main() {
  int N, K, b;
  cin >> N >> K;
  string str;
  cin >> str;
  vector<vector<int>> a(N, vector<int>(2));
  for (int i = 0; i < N; i++) {
    if (str[i] == '(') {
      a[i][0] = 1;
    } else {
      a[i][0] = 2;
    }
  }
  while (true) {
    for (int i = 0; i < N; i++) {
      if (a[i][0] == 1 && !a[i][1]) {
        b = i;
        continue;
      }
      if (a[i][0] == 2 && !a[i][1]) {
        a[b][1] = a[i][1] = 1;
        if (b == K - 1) {
          cout << i + 1 << endl;
          return 0;
        } else if (i == K - 1) {
          cout << b + 1 << endl;
          return 0;
        }
        break;
      }
    }
  }
}