PROGRAM Hello;

VAR
	filein : text;
	mychar : char;
	highest, column, row, pass : integer;

BEGIN
	highest := 0;
	column := 0;
	row := 0;

	assign(filein, 'input');
	reset(filein);
	repeat begin
			read(filein, mychar);

			case mychar of
				'F': row := row shl 1;
				'B': row := (row shl 1) or 1;
				'L': column := column shl 1;
				'R': column := (column shl 1) or 1;
				otherwise begin
					pass := row * 8 + column;

					if pass > highest then
						highest := pass;

					row := 0;
					column := 0;
				end
			end;
		end;
	until eof(filein);
	close(filein);

	writeln('Largest boarding pass found is ', highest);
END.