Each student in the class has chosen one mathematics and one physics problem out of the set of 20 mathematics and 16 physics problems such that different students choose different pairs of problems. Given that for each student, at least one of the problems chosen by him is chosen by at most one more student, determine the maximum possible number of students in the class.
Correct solutions by,
- Toshihiro Shimizu, Kawasaki, Japan
- Mehmet Ali Yildirim, Florya Final Anadolu Lisesi, İstanbul, Turkey
- Tomas Jurik, Kosice, Slovakia
- Abdulkadir Tanrıverdi, Eskişehir, Turkey
- Henrik Aberg, Gothenburg, Sweden
- Burak Can Biner, Turkey
- Roger Bengtsson Lund, Sweden