Abstract: 
This entry contains formalisations of the answers to three of
the six problem of the International Mathematical Olympiad 2019,
namely Q1, Q4, and Q5. The reason why these
problems were chosen is that they are particularly amenable to
formalisation: they can be solved with minimal use of libraries. The
remaining three concern geometry and graph theory, which, in the
author's opinion, are more difficult to formalise resp. require a
more complex library. 
BibTeX: 
@article{IMO2019AFP,
author = {Manuel Eberl},
title = {Selected Problems from the International Mathematical Olympiad 2019},
journal = {Archive of Formal Proofs},
month = aug,
year = 2019,
note = {\url{http://isaafp.org/entries/IMO2019.html},
Formal proof development},
ISSN = {2150914x},
}
