Yandex interview questions

The whole process took 60+days. I was interviewed for yandex search department. Recruiter found me on LinkedIn. The whole process consisted of 4 interviews. First on-skype with product head(1,5 hours) - I was asked about my previous experience and different product cases I have solved with metrics description. Second part was at yandex office with 4 employees: 2 product heads, 1 analyst, 1 software architect. This part took over 5 hours, I was asked common question about project management, statistics and metrics(analyst), architecture of high-load services (software architect) and product questions(product head). After I passed it successfully - I was invited to third part with project manager and product head, I was asked questions about main product scenarios and product design of yandex serp for one scenario. I didn't covered all questions and scenarios, so I was declined for this search dept and they invited me for fourth interview with another search dept, there I was asked general project and product management questions and passed it well( according to final feedback). But got no offer, I suppose it's because of not so successful third part.

3 step interview: - HR - technical for 5 hours - many questions about programming language, a bit about algorithms - with managers - only questions about life, previous job, etc. Not hard, but requires depp knowledge of programming language