A square is placed in the plane and a point P is marked in this plane with invisible ink. A certain person can see this point through special glasses. One can draw a straight line and this person will say on which side of the line the point P lies. If P lies on the line, the person says so. What is the minimal number of questions one needs to find out if P lies inside the square or not?(Folklore) geometrycombinatorial geometrycombinatorics