You are trapped in a room that doesn't have any windows, doorways, or doors, only walls made of cement. You only have a calender, a mattress, and a peice of paper. You have to eat, drink, and then escape in that order.
How do you do it?
The springs inside the mattress provide water. You eat the dates in the calender and you rip the paper in half. You put the halves together to make a whole. You climb through the hole and escape.