import java.util.Scanner;

public class Beth {

    static String line;
    static int index;

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

        index = 0;
        line = sc.nextLine();

        System.out.println(cal());

    }

    public static long cal() {
        index++;
        long value = 0;
        char curr = line.charAt(index);
        while (line.charAt(index) != ')') {

            if (value == 0) {
                value = cal();
            } else {
                value *= cal();
            }
        }
        index++;
        return value + 1;
    }
}