import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k = in.nextInt();
        String s = in.next();
        char[] c = s.toCharArray();

        int mv = 1;
        k--;
        if(c[k] == ')') mv = -1;
        int cnt = 0;
        for(int i=k+mv; cnt!=1; i+=mv) {
            if(c[i] == c[k]) cnt--;
            else cnt++;
            if(cnt == 1) {
                System.out.println(i+1);
                break;
            }
        }

        in.close();
    }
}