.
                
                                    F
                           r      r   i        r
                        i          e   n         i
                      e             d              e
                     n              s                n
                    d               F                 d
                   s              r     i                s
                   F             e      n              F
                    r            d       s              r
                     i              F    r              i
                      e                i               e
                        n             e             n
                            d         n        d
                                       d