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

#define ll long long
#define vvi vector<vector<int>>
#define vec vector
#define pq priority_queue
#define all(v) (v).begin(), (v).end()
#define rep(i, n) for (int (i) = (0); (i) < (n); ++(i))
#define repp(i, m, n) for (int (i) = (m); (i) < (n); ++(i))
#define debug(x) cerr << #x << ": " << x << endl;
#define debug2(x, y) cerr<<"("<<#x<<", "<<#y<<") = "<<"("<<x<<", "<<y<<")"<<endl;
#define debug3(x, y, z) cerr<<"("<<#x<<", "<<#y<<", "<<#z<<") = "<<"("<<x<<", "<<y<<", "<<z<<")"<<endl;
#define debugB(x, y) cerr<<#x<<": "<<bitset<y>(x) << endl;
#define line() cerr << "---------------" << endl;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};

template<typename T>
void printA(vector<T> &printArray, char between = ' ') {
   int paSize = printArray.size();
   for (int i = 0; i < paSize; i++) { cerr << printArray[i] << between;}
   if (between != '\n') {cerr << endl;}
}

// ------------------------------------------------------------------------------------------

int main() {
   int n, k;
   string s;
   cin >> n >> k >> s;
   k--;
   vec<int> imos(n);
   int cnt = 0;
   repp (i, 0, n) {
      if (s[i] == '(') {
         cnt++;
         imos[i] = cnt;
      } else {
         cnt--;
         imos[i] = cnt+1;
      }
   }

   int ans = 0;
   if (s[k] == '(') {
      for (int i = k+1; i < n; i++) {
         if (s[i] == ')' && imos[i] == imos[k]) {
            ans = i + 1;
            break;
         }
      }
   } else {
      for (int i = k-1; i >= 0; i--) {
         if (s[i] == '(' && imos[i] == imos[k]) {
            ans = i + 1;
            break;
         }
      }
   }

   cout << ans << endl;

   return 0;
}