Furrows#826
On the parquet floor of a local physics and mathematics academy, a vandal has carved several grooves, all running parallel to the walls. The school administration has decided to paint all these grooves blue. Having prepared everything necessary for the task, the head painter wondered whether it is possible to paint all the grooves without lifting the roller from the floor and without painting any groove more than once. Your task is to determine whether such a painting is possible.
The first line contains an integer (1 \le N \le 100), the number of grooves made by the vandal. Then integers follow, representing the coordinates of the endpoints of each groove: X_1, Y_1, X_2, Y_2 (-1000 \le X_1, Y_1, X_2, Y_2 \le 1000).
Print NO if such a painting is not possible, and YES if it is possible.
Example 1