#include <bits/stdc++.h> 
using namespace std;
#include <stdio.h>
#include <iomanip>
#include <iostream>
#include <string>
#include <algorithm>

int main(){
  string a;
  cin >> a;
  int number =1;
  for(int i=0;i<a.size();i++){
    if(a.at(i)=='R'){
      number=number*2+1;
    }
    else number=number*2;
  }
  cout << number;
}