In a class of $$52$$ students, there are $$30$$ swimmers, $$35$$ cyclists and $$42$$ playing table tennis.  What is the least possible number of students who play all three sports? 
Overseas Competition->Knowledge Point->Counting Modules->Inclusion-Exclusion Principle->Inclusion-Exclusion Principle for Three Sets Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations