popd [ {+|-}n ]
       Remove an  entry  from  the  directory  stack,  and
       perform  a  cd  to  the new top directory.  With no
       argument, the current top  entry  is  removed.   An
       argument  of the form `+n' identifies a stack entry
       by counting from the left of the list shown by  the
       dirs  command,  starting with zero.  An argument of
       the  form  -n  counts  from  the  right.   If   the
       PUSHD MINUS  option is set, the meanings of `+' and
       `-' in this context are swapped.
