This was by far the worst interview process I had ever experienced.

I applied online and was contacted by a recruiter for a specific role. She never contacted me back to set up a time, but later that week, an engineer called me and was under the impression our interview was confirmed for that time. I was completely unprepared. I told him that the recruiter hadn't set up a time, but he gave me the impression that once it was confirmed with him, he couldn't reschedule, so it was either then or never.

I went through the interview but wasn't ready and, not surprisingly, did not perform very well.

Find the first non-repeated element in C.