There are 100 perfectly logical green eyed dragons on an island. A dragon cannot see the colour of its own eyes but can see the eye colour of the other dragons. The dragons have a rule that they cannot talk with each other about the colour of their eyes. Should any dragon gets to know for sure that its eye colour is green then that dragon gets transformed at midnight into a sparrow. A visitor who can only speak the truth tells them that at least one of them has green eyes. What happens next?"
