sub fact{
            (map{$_[0]*=$_}1..$_[0]-1)[-1]||1   # 33

          # only 30 char for numbers bigger than 1
          # (map{$_[0]*=$_}1..$_[0]-1)[-1]


}
[download]

perl -e "sub fact{$x=$_;$x<0?'E':(map{$x*=$_}1..$x-1)[-1]||1} print ma
+p{fact($_),qq(\n)}@ARGV " 0 1 3 -1

1
1
6
E
[download]