Notes

TODO: https://codeforces.com/gym/100551, https://codeforces.com/blog/entry/15296

http://memphis.is-programmer.com/2015/8/7/linkcutmemphis.99293.html

https://github.com/bqi343/USACO/blob/master/Implementations/content/data-structures/ETT.h

https://codeforces.com/blog/entry/18369