Permalink /Êtegory%/%postname%/

Custom, specify below
Custom structure: /%category%/%postname%/
Category base: topic

then the category is /topic/%category%/
but the post link is /%category%/%postname%/
not /topic/%category%/%postname%/
and all the posts in the second category
i want the link like this /topic/parent%category%/second category/%postname%/

how to do this?
thanks for help