I woke up, and like every morning, I took a shower, ate breakfast and got dressed to get out and go to work. I put on my coat, opened the door and locked it behind me. I walked down the stairs, and once I got to the third floor, there was the second floor in its place. I then decided to go back to the fifth floor, where my apartment was, and try again. I thought I may have lost the third floor along the way.
Once I got back to the fifth floor, I found the sixth floor. I then went down the stairs back to the second floor to see if the third floor was perhaps back, but there were no traces of the third floor. I continued from the second floor to the first and then to the ground floor, where there was the exit.
I opened the exit door to get out because, maybe, the third floor had gone out too without anyone noticing it. However, I found myself back into my apartment as if I had just come back through the balcony door.
I closed the balcony door behind me and walked towards the entrance door. I turned the handle, but it was locked because I had locked it a few moments earlier the first time I got out. I unlocked it, went out for the second time from my fifth-floor apartment, and locked the door behind me again. It was then that I realised I was on the third floor. At last, I did find it!