import java.io.*;

class Yuki22 {
  public static void main(String[] args) throws IOException {
    InputStreamReader is = new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(is);
    String s = br.readLine();
    int n,k;
    String[] sa = s.split(" ");
    n = Integer.parseInt(sa[0]);
    k = Integer.parseInt(sa[1]);
    String s2 = br.readLine();
    int x;
    x=s2.length()+1;
    if(s2.charAt(k-1)=='('){
      int a;
      a=1;
      for(int i=k; i<s2.length(); ++i){
        if(s2.charAt(i)=='('){
          a++;
        } else {
          a--;
          if(a==0){
            x=i;
            break;
          }
        }
      }
    } else if(s2.charAt(k-1)==')'){
      int a;
      a=1;
      for(int i=k-2; i>=0; --i){
        if(s2.charAt(i)==')'){
          a++;
        } else {
          a--;
          if(a==0){
            x=i;
            break;
          }
        }
      }
    }
    x+=1;
    System.out.println(x);
  }
}