This one is kinda hard to describe, so I'm including an image. Four people are standing in a row and all are looking to the right (EDIT: On the image, the fourthperson is looking left. That doesn't matter, because nobody can see through the wall). First and third person have blue hat, second and fourth have red hat. There's a wall between third and fourth person. Nobody knows what color is their hat. Everybody can only see hats of people on their right side (left/right sides are from the perspective of us, seeing them from the side). Nobody can see through the wall. For example first person can see the second and the third person. The second can only see the third person. They know that two of them have red hat and two of them have blue hat. They are told that if anybody says aloud the color of their hat, they are free to go. (They are captives or something). If anybody says the wrong color, they are all gonna be killed. They can't obviously turn around, talk to each other or something like that. They can't guess. Are any of them going to tell his hat's color?