One day, you enter your house...and find it has been burglarized. On the table, a note says, "Thank you for your valuables. In return, I left a gift in the basement." Quite confused, you head down to the basement. On the table, there are 9 boxes and a piece of paper. The paper says:
There are 9 boxes on the table. There is one box that has a diamond ring, 4 boxes that will explode, and 4 boxes that contain a deadly gas. As you will notice, the door to the basement has swung shut and locked, because of my trickery. The ring box has a key, to open the door.
The boxes on the left and right are the same. The one in the center is the same as the one to its right. Twice, two poison gas boxes are next to each other. To the left of the center is a poison box.
If you pick up a poison box or exploding box, you'll die. Which box is the safest choice?