You've lived in your residence since you were born.

One day you were in the elevator in the building you live in. You are alone with another man that you've never seen in the building before.

It's not that weird since he could be a guest or someone else...but suddenly the elevator stops, the lights turned off and then on, the man is gone.

You were sure you were with someone, but how could the person just disappear? Was it a ghost?