import java.util.Scanner;

public class Beth {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        scanner.nextInt();
        scanner.nextLine();

        String row = scanner.nextLine();
        int result = 0;

        for (int i = 0; i < row.length() - 1; i++) {
            char current = row.charAt(i);
            char next = row.charAt(i + 1);

            if (current == '(' && next == ')') {
                result++;
            } else if (current == ')' && next == ')') {
                result++;
            }
        }

        System.out.println(result);
    }

}