16
boundary
1
1  0.  0.  0.  24
    2      0.00      0.80      6.10      0.80
    3      6.10      0.80      6.50      0.80
    4      6.50      0.80      8.00      0.80
    5      8.00      0.80      8.00     23.20
    6      0.00     23.20      8.00     23.20
    7      0.00      1.60      6.10      1.60
    8      0.00      3.60      6.10      3.60
    9      0.00     18.80      6.10     18.80
   10      0.00     21.20      6.10     21.20
   11      6.10     21.20      6.50     21.20
   12      6.50      0.80      6.50     21.20
   13      6.10      0.80      6.10      1.60
   14      6.10      1.60      6.10      3.60
   15      6.10      3.60      6.10     18.80
   16      6.10     18.80      6.10     21.20