They had no idea how to conduct a technical interview. Based on knowledge, I had a feeling they are students asking their professor's favorite question. Which wasn't quite suitable in given situation.
Interview questions [1]
Question 1
The first - non-technical - interview was perfect. The second - technical - was a disaster. The most difficult part sometimes was to understand what they mean. They had difficulties to express their thoughts in English. Everyone who programmed for few years can check new candidate knowledge in 15 minutes. They failed totally.