# code: http://golf.shinh.org/reveal.rb?Grouping/tails_1645506898&nbb
# target Nibbles version: 0.23
# commenter version: 0.1.2.181

: #(append):[chr] 
    \ #(reverse):[int] 
        `< #(sort):[int] 
            . #(map):[int] 
                =~ #(group by (also sorts)):[[int]] 
                    _ #(= ints):[int] 
                    $ #(= A):int <--arg( A:int ) 
                , #(length):int <--arg( B:[int] ) 
                    $ #(= B):[int] 
    "\n" #(string):[chr]