Four prisoners are sentenced to death.
On them have put on two white hats and two black hats. Men initially don't know what color a hat they carry. Four prisoners, have built one after another (see the drawing) in such a way that:
The person 1 can see men 2 and 3.
The person 2 it is possible to see the person 3.
The person 3 doesn't see anybody.
The person 4 doesn't see anybody.
The judge has promised any prisoner who has called color of the hat freedom.
Question: Who called color of the hat the first? )))