import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt(), k = sc.nextInt(), idx = 0;
		int[] t = new int[n], st = new int[n];
		String s = sc.next();
		for(int i = 0; i < n; i++){
			if(s.charAt(i) == '('){
				st[idx] = i;
				idx++;
			} else {
				idx--;
				t[i] = st[idx];
				t[st[idx]] = i;
			}
		}
		System.out.println(t[k-1]+1);
	}
}