Serraview interview questions

Through a agency. First round is a pure live coding challenge. Spend 5 mins talked about the software they are doing and then come to the desk with a paper describing the task to be solved. The time is limited to 1 hour and you are coding with a senior developer. If you pass, there will be 2nd interview talking about what you have done before. I didn't fully solve the code challenge. The question itself is not easy especially you are sitting next to someone and use their mouse/keyboard and a VS plugin. The shortest solution may take 70 lines of code if you are very clear of what you are doing. P.S. the office location is good but no reception and no ground floor hallway. About 20 people are working there.