## Editorial for Bộ bốn có tổng bằng 0

Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.

Submitting an official solution before solving the problem yourself is a bannable offence.

Authors: ShyWoou

$$4$$ vòng for to $$\color{green}{\textbf{AC}}$$