program karike

{$APPTYPE CONSOLE}

uses
  SysUtils;
var
s: string;
br, i, modifikator: integer;
pare,zagsuma: longint;

begin
  { TODO -oUser -cConsole Main : Insert code here }
  readln(s);
  br:=0;
  pare:=0;
  modifikator:=1;
  zagsuma:=0;
  for i:=1 to length(s) do begin

                                if s[i]='O' then begin
                                                       pare:=pare+modifikator;
                                                       modifikator:=modifikator*2;
                                                       br:=br+1;
                                                       if br=15 then begin
                                                       zagsuma:=1000000000;
                                                       break; end;

                                                  end;

                                 if s[i]='X' then begin
                                                  pare:=0;
                                                  modifikator:=1;
                                                  br:=0; end;

                                 if s[i]='B' then zagsuma:=zagsuma + pare;

end;
writeln(zagsuma);
readln;
end.