Two phone interviews, each an hour long and followed by an assignment that I have to submit before midnight. The difficult level is similar in both interviews, I was asked about my background, some specific questions about past project. Then questions about data structure, system design, how to improve performance of a large system. Two interviewers were from different departments, and they introduced themselves as well as their current projects. In the end of each interview, they asked me to solve a BST problem, we discuss the solution first, then he asked me to write the code of that solution(even though it may not be the best solution) and email them after the phone interview.