As a test of intelligence, BrainBashers academy sits two candidates in closed room.
The invigilator has three stickers, two white and one black.
Upon each of their foreheads he places a sticker at random, so that neither candidate can see their own sticker.
The candidate who identifies their own sticker first will be allowed entry into BrainBashers academy.
After a few minutes, one of the candidates figured he had a white sticker. How?