# code: http://golf.shinh.org/reveal.rb?Digit+depth/darrenks_1644422075&nbb
# target Nibbles version: 0.23
# commenter version: 0.1.2.181

! #(zip with):[chr] 
    =\ #(scanl):[int] 
        @ #(= fstLine):[chr] 
        _ #(= fstInt):int <--arg( B:chr A:chr ) 
        + #(add):int <--arg( D:chr C:int ) 
            - #(subtract):int 
                % #(modulus):int 
                    + #(add):chr 
                        $ #(= D):chr 
                        ~ #(auto = 1):auto 
                    3 #(integer):int 
                ~ #(auto = 1):auto 
            @ #(= C):int 
    _ #(= fstLine):[chr] <--arg( E:int ) 
    ~ #(zipop: by):null 
    / #(foldr1):chr <--arg( G:int F:chr ) 
        : #(append):[chr] 
            \ #(char class):[chr] 
                @ #(= F):chr 
                D #(not.isDigit):null 
            #(implicit arg = G):int 
        #(implicit arg = I):chr <--arg( I:chr H:chr )