import java.util.*;
import java.math.*;
import java.io.*;

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