$6.$ Consider the following sequence of stack commands: push$($a$),$ push$($b$),$ push$($c$),$ pop$().$push $($d$),$ push $($e$),$ pop$(),$ pop$(),$ pop$(),$pop$()$

a$.$ What is the order in which the elements are popped? $($give a list and indicate which was popped first$)$

b$.$ Change the position of the pop$()$ commands in the above sequence so that the items are popped in the following order: b$,$d$,$c$,$a$,$e you are not allowed to change the ordering of the push commands.