question: What are the dates of the latest logon of the students with family name "Jaskolski" or "Langosh"?
#1 return students 
#2 return #1 with  family name Jaskolski 
#3 return #1 with  family name Langosh 
#4 return #2 ,  #3 
#5 return logons of #4 
#6 return the   latest of #5 
#7 return the   dates of #6