If field is empty - clear another field too

If field is empty - clear another field too

How would I add to the below scrip to say:

if Enrolled_Classes field is empty (ie all classes have been deselected) clear any value in Type_of_Student field?

if(Enrolled_Classes.Stream == "Cheer Advanced" || Enrolled_Classes.Stream == "Cheer Elite" || Enrolled_Classes.Stream == "Dance")
{
input.Type_of_Student = "Other";
}
else
{
input.Type_of_Student = "Cheer Sport, Cheer Fun or non-competitive ONLY";
}