s S = show Set S
i V S = insert value V in Set S
d V S = remove value V from Set S
m V S = check if value V is in Set S
c S = cardinality of Set S (#elems)
+ S T R = put (S Union T) in Set R
* S T R = put (S Intersect T) in Set R
r F S = read values from file F into Set S
q = quit