1                                2                                   3                                4

          25                                 26                               27                               28

          17                                18                                19                               20

         45                               46                                47                                48

         33                                34                                35                                36

         53                               54                                55                                 56

          29                               30                                31                                32

          21                                22                               23                                24

          13                                14                                15                               16

           9                                10                                11                               12

         37                                38                                39                                40

         57                                58                                59                                 60

         41                               42                                43                                44

         49                               50                                51                                52

           5                                 6                                  7                                  8