Introduction - If you have any usage issues, please Google them yourself
The set of operations: pay, and, filling (difficulty coefficients: 1.1)
Complete: capital letters A ~ Z
Requests to realize the following functions:
1, set of input: automatic take out repetition and illegal characters
2, set display: output all elements of collection
3, output a given set of BuJi
4, output given the intersection of two sets and and sets