import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String line = scanner.nextLine().trim();
        String[] parts = line.split(" ");
        int height = Integer.parseInt(parts[0]);
        String road = parts.length > 1 ? parts[1] : "";
        int result = searchNode(height, road);
        System.out.println(result);
        scanner.close();
    }

    public static int searchNode(int height, String road) {
        int root = (1 << (height + 1)) - 1;

        if (road.isEmpty()) {
            return root;
        }

        int label = root;
        int local = 0;

        for (char move : road.toCharArray()) {
            if (Character.toLowerCase(move) == 'l') {
                local = 2 * local + 1;
            } else if (Character.toLowerCase(move) == 'r') {
                local = 2 * local + 2;
            }
        }

        label -= local;
        return label;
    }
}