https://www.commonlounge.com/discussion/55e14de95aed4baa84f61bcb4c14ca3c
https://codeforces.com/blog/entry/23054
https://github.com/lnishan/awesome-competitive-programming
https://codeforces.com/blog/entry/47822
https://codeforces.com/blog/entry/82143
https://codeforces.com/blog/entry/75742
https://codeforces.com/blog/entry/66909
https://codeforces.com/blog/E869120