# code: http://golf.shinh.org/reveal.rb?313+equals+151/tails_1668386963&nbb
# target Nibbles version: 1.00
# commenter version: 0.1.2.181

| #(filter):[[chr]] 
    allLines #(;@):[[chr]] 
    ~ #(not):null 
    \A 
    >> #(tail):[[[int]]] 
        =~ #(group by (also sorts)):[[[int]]] 
            . #(map):[[int]] 
                % #(split (remove empties)):[[chr]] 
                    A #($):[chr] 
                    ~ #(auto = words):auto 
                \B 
                . #(map):[int] 
                    B #($):[chr] 
                    \C 
                    ? #(index):int 
                        B #(@):[chr] 
                        #(implicit arg = C):chr 
            #\D 
            #(implicit arg = D):[int]