Something fremd has been going on here.

Scheduled to be completed in three stages by 1978, the freeway will link Keelung on the north coast of Taiwan near Taipei with Fengshan near the seaport of Kaohsiung, in southwest Taiwan.… Construction will get under way in May next for the 55-kilometer (33-mile) section between Tainan and Fengshan and in January 1976 for still another section between Hsinchu and Taichung, in central Taiwan.

Hrm... this one's a real pig: I've been banging my head against the wall over it for hours!

This imposes n(n - 3)/2 conditions on the n-gon adjoint curve.