Find as much bricks as possible

There are n floors, N> = 3. Each floor has a diamond in the elevator,Decision makers can tell the size of diamond,That is to say, he has the ability to correctly sort the diamond he has seen by size,But he does not know
The greatest diamond is big, and I don't know how small the smallest one is.He took the elevator with a transparent door from the first floor to go upstairs (This means that he can see the size of the diamond on each floor), but he can only stop once.Excuse me
How can we make the decision to maximize the size of the diamond?

 

 

I haven't thought about solving the question I just saw yet. I will try it first.