This is an explanation (?) of a certain programming contest. It's specifically designed to give you a super-fast overview. You can watch this video even if you haven't participated in the contest. Contest site: https://atcoder.jp/contests/abc186 Source code: A https://atcoder.jp/contests/abc186/su... B https://atcoder.jp/contests/abc186/su... C1 https://atcoder.jp/contests/abc186/su... C2 https://atcoder.jp/contests/abc186/su... D https://atcoder.jp/contests/abc186/su... E https://atcoder.jp/contests/abc186/su... I'm also on Twitter: / evima0