question: Show the carriers that have both phones with memory smaller than 32 and phones with memory bigger than 64.
#1 return phones  
#2 return memories of  #1 
#3 return #1 where #2 is  lower than 32 
#4 return #1 where #2 is  higher than 64 
#5 return #1 of  both #3 and  #4 
#6 return carriers of  #5