I live in a house converted into a shop and two flats. The flats are on the second and third floors and accessible by the same staircase. On the staircase I found a tenner. I know it can't be my flatmates as he is away. I don't know if it's mine or isn't mine and I don't know if it belongs to the guy downstairs or doesn't belong to the guy downstairs.
I don't want to take his tenner but don't want to leave my tenner for him to pick up. I did try to knock on his door and ask if it was his (not necessary expecting an honest answer) but he was out.
a) Keep it
b) Replace it on the stairs
c) Give it to charity?
d) Stop worrying and learn to be a mature adult who makes his own decisions without consulting the internet?