#include <iostream>
#include <string>

using namespace std;

int main(){
  string memory;
  getline(cin, memory);
  int now = 1;
  for(int i = 0; i < memory.size(); i++){
    now *= 2;
    now += memory[i] == 'R';
  }
  cout << now << "\n";
  return 0;
}