Central European Olympiad in Informatics
The Central European Olympiad in Informatics (CEOI) is an annual informatics competition for secondary school students. Each of the participating central European countries (plus one or two guest countries, and a local team from the host area) sends a team of up to four contestants, a team leader and a deputy team leader.
Source: Wikipedia — Central European Olympiad in Informatics (CC BY-SA 4.0)