Countries bordering a Country precisely East of it
Can you find the 20 pairs of bordering countries such that when flying between their geographical centers you need to follow a bearing close to 90°?
Data from Portland State University (https://www.pdx.edu/econ/country-geography-data), for missing countries from CIA (https://www.cia.gov/library/publications/the-world-factbook/fields/2011.html)
The bearing shown is the 'rhombus' bearing you need to follow to fly from the 'West' country to the 'East' country