Three naughty students have not completed the home–work given by their Physics teacher. The ill–tempered Physics teacher is now ready to punish the three erring students but then he gives them a chance. He makes them stand in a row in such a way that the student at the rear can see the backs of remaining two students, the student in the middle can see the back of the student in front, and the student in front cannot see anyone. The Physics teacher shows them five caps. Three of the caps are black and two of the caps are white.