question: For each position, what is the maximum number of  hours for students who spent more than 1000 hours training?
#1 return students 
#2 return positions of #1 
#3 return hours  spent training of #1 
#4 return #1 where #3 is higher than 1000 
#5 return hours  spent training of #4 
#6 return the  highest of #5 for each  #2