A collection of 40 elements. Mathematically, these 40 sports events can be represented by a set, which contains 40 elements. You can use capital letters including A, B and C to represent each sport, which will form a set. Each letter represents a specific sports event, and the number of elements in the collection is 40 major items. Using set representation, 40 different sports events can be clearly represented, which is convenient for statistics and operation.