Email   Blog   Facebook   YouTube   Twitch   Discord   Github


  •  CV
  •  Photos

Teaching (OTIS)


  •  For beginners
  •  Problems
  •  MOP
  •  ELMO
  •  USEMO


  •  Puzzle hunts
  •  Twitch
  •  Discord

plz learn code

  •  Filesys
  •  Learning path


  •  EGMO book
  •  Napkin (v1.5)
  •  Course notes


  •  Mentors
  •  Quotes
  •  FAQ's


  •  Rec letters

Buy Me a Coffee at

MOPper World 2.0

Not an official logo, but comedic

About MOP#

This section of the website is dedicated to public-facing material from various years of MOP. It’s similar in spirit to the MOPper world that ran between 1997 and 2004. This page isn’t a puzzle.

MOP is a three-week camp now held at CMU. In 2020 and 2021, the camp was run on Discord. Prior to 2015, the camp was held in Nebraska. See FAQ CR-7 for invitation rules.

Today, the camp is headed by director Po-Shen Loh and assistant academic director Evan Chen. (There is no academic director or assistant director.) Staff includes instructors, RA‘s, and teaching assistants (aka graders).

For many years, the official name for MOP was “MOSP”, but the letter S was universally ignored by staff and students, and its omission became an ongoing gag. The S was finally officially deleted in 2017.

MOP Puzzle Hunt#

  • MOP 2021 puzzle hunt, a miniature one-round hunt written by Evan Chen, Isabella Quan, Sanjana Das, and Serena An.

T-shirt designs#

Traditionally, MOP T-shirts are printed in black on grey. With the exception of 2020, usually there is only a front design, and the back contains everyone’s signature.

2016. 2017. 2018; reference to 2017 G8. 2019; reference to ELMO 2019/2. 2020. 2020; reverse. 2021; reference to USAMO 2021/3. 2021; reverse.


  • The ELMO is written by returning MOPpers for new MOPpers, featuring “teams” and coordination. See ELMO page.
  • The Mock IMO is run by staff using ISL; it also features a mock coordination. You can download the problems here:
  • The staff also provide MOP homework to work on before camp starts, mostly for fun and so people have something to talk about at airport. Here are recent homework problems:


Singing troupe#

The MOP Singing Troupe is a tradition dating back to around 2010, started by Evan o’Dorney; it starts and ends the closing ceremony. Here are recent songs we peformed:


Updated Fri 3 Sep 2021, 21:09:44 UTC by 55260fba4864