If the mountains classification is Mathias Frank, and the General Classification is Fabian Cancellara, what is the Points classification?
create table table_27573848_18 (points_classification varchar, general_classification varchar, mountains_classification varchar, PRIMARY KEY (points_classification))
select points_classification from table_27573848_18 where general_classification = "fabian cancellara" and mountains_classification = "mathias frank"