this interactive problemnow serval senior high school student Japari Middle School however way school pond dangerous snake the pond represent n time n grid the snake head tail different cell body series adjacent cell connect head tail selfintersecte if Serval hit head tail snake bite dieluckily special device answer follow question pick rectangle tell number time need cross border rectangle walk cell cell snake head tail the picture possible snake possible query answer 4 today Serval get late time 2019 query as good friend help find position head tailnote cell adjacent common edge grid snake body length 0 mean adjacent head tailalso note snake sleep will not serval device and what s obvious snake position depend query