Heck, solve the mystery:
On the water is a ship, a staircase is lowered from it, the distance between stairs at the staircase is 15 cm. The water rises at a speed of 30 cm per hour. After how long will the 5th staircase from below hide under water?
WOW: It will not hide under the water, because the forest rises with the boat as the water arrives!
XH: O_O
Sorry, but to go home?
She is not at home, she has left.