import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		String s = sc.next();
		int n = 1;
		for (int i=0; i<s.length(); i++) {
			if (s.charAt(i) == 'R') n *= 2;
			else n = n*2 + 1;
		}
		System.out.println(n);
		
	}
}