Four men are standing in a line as shown above and they cannot turn their heads. There is a brick wall between A and B
that they cannot see through. They know that they each have one hat, and that of the four hats two are black and two are
white. They cannot see the color of the hat that they are wearing. In order to be released from the line, they must call
out the color of their hat. If they are wrong, no one can leave. They are not allowed to talk to each other, and they
have been given ten minutes to figure out their hat color.
After 1 minute, one of them calls out -- which one called out?
How can he be 100% certain of the color of his hat?
This is not a trick question and there are no outside influences nor any other ways of communicating. They cannot move
or see behind them, nor can they see through the wall.