axiom
#
   G(-10,-10,-10)
   X(90)  Y(90)  Z(90)
   S(20)
#
   c;

rules 2
  c= [ #S(S/3)#
       f+f-
       [
        [c^ff&c]
        -f^ff+
        [c^ff&c]
        ff^f
        [c^f&c^f&c]
       ]
     ];
end

rules 1
   c= [
       [    (F+F+F+F+) ^ f & + (F-F-F-F-) ]      
       [^ < (F+F+F+F+) ^ f & + (F-F-F-F-) ]     
       [+ > (F+F+F+F+) ^ f & + (F-F-F-F-) ]         
      ];
end