We've talked about the students. Now it's time to talk about the leaders: what they do and where they've been for the past few days.
A few days before the IMO exam, the leaders are whisked away to a "top secret location" (so naturally everybody knows where they will be) to decide on the six questions that will be in the paper. A preprepared list of possible questions called the 'IMO Shortlist' is given to the leaders to try for themselves before they begin the jury meetings where they make the final cut. The questions in the IMO Shortlist are proposed by various mathematicians around the world. Some are too easy, some are far too hard.
After mulling over the questions, the leaders assemble again (like the Avengers) to share their opinions on what the paper should be. The leaders vote on different propositions with a placard (although I prefer the term 'sceptre') and the majority votes win.
There's obviously no communication allowed between the leaders and their teams to prevent any cheating happening. They are reunited with their students after the second exam.
So after all the questions have been decided, it's time to prepare for the 4.5 hour exam. During the first 30 minutes of the exam, the contestants are allowed to ask questions clarifying anything their confused about, like the wording of a question. Sometimes the questions are justified, like asking if certain scenarios are possible, but others are completely pointless (like the ones Natalia asked). The leaders then present the questions to the Jury (i.e. the rest of the leaders) and they collectively come up with an answer to send back to the contestant.
It may be over for the students when the exam is finished, but for the leaders (and deputy leaders), the hard work has just begun. Now that both exams are officially over, the leaders and their deputies of every participating country are going through every single bit of writing that their team wrote, hoping to find material that can be awarded marks. Some proofs that the contestants submit are obviously complete, others may be partially complete and some may have no value at all. This stage is called 'coordination'. We'll keep you updated as the New Zealand scores roll in!
All photo credits go to Geoff Smith, the leader of the UK team, a member of the IMO Advisory Board, the newly appointed chair of the IMO, and two time IMO Golden Microphone winner.