#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <stack>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
#define SQR(X) ((X)*(X))

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;
/* ここからが本編 */

int main(void)
{
   int i,j;
   int n,k;
   char c;
   int rep;
   stack<int> a;
   cin >> n >> k;
   for(i=1;i<=n;i++) {
      cin >> c;
      if(c == '(') a.push(i);
      else {
         if(k == i) {
            rep = a.top(); break;
         }
         else if(a.top() == k) {
            rep = i; break;
         }
         else a.pop();
      }
   }
   cout << rep << endl;
   return 0;
}