# code: http://golf.shinh.org/reveal.rb?Sign+of+permutations/tails_1643893872&nbb
# target Nibbles version: 0.23
# commenter version: 0.1.2.181

`* #(product):int 
    . #(map):[int] 
        `_ #(subsequences):[[int]] 
            ~ #(auto = 2):auto 
            _ #(= ints):[int] 
        / #(foldr1):int <--arg( A:[int] ) 
            $ #(= A):[int] 
            `$ #(signum):int <--arg( C:int B:int ) 
                - #(subtract):int 
                    @ #(= B):int 
                    #(implicit arg = C):int