Planarity

Description: Ðàñïóòàéòå ïàóòèíêó òàê, ÷òîáû íè îäíà íèòî÷êà íå ïåðåñåêàëàñü. Çâó÷èò ïðîñòî, à ñëîæíî äåëàåòñÿ.
Instructions: