"The challenge is if certain types of people are doing something, it's difficult for other people to break into it," said Po-Shen Loh, the head coach of last year's winning U.S. Math Olympiad team.

I tried to implement my idea in perl, but I just couldn’t get the class relationships to work (the attributes and resource types each needed to be classes, according to the design in my head).

The disease includes a range of tumour types occurring in the tissues and organs in the head and neck, for example salivary glands and mucus membranes.