[JAVA] Try to carry out paiza skill check

There are many problems to implement Java program problems, so I decided to use paiza, which I personally use frequently. There are skill check problems in paiza, and since they are allowed to be disclosed to the outside, they politely write "Please use them as teaching materials". Also, there are many languages other than Java, so I think it's convenient when you want to study another language.

Skill check problem

You can challenge up to B rank (up to S rank for problems without external disclosure).

There was a part where I couldn't immediately understand how the problem was raised and the conditions, so I'd like to try a sample problem first and get a feel for it. There is no time limit for level-up problems, so it's easy to repeat what you've forgotten.