do we really have to output exactly 10 digits after decimal point? see submission 77981 vs submission 77947

No. Sorry, we make a misjudge in problem F. So, we will take a rejudge for all submits of problem F. 

Sorry, we make a misjudge in problem F. So, we will take a rejudge for all submits of problem F. 

I got "Accepted" for problem "J Tree Reconstruction", but the leaderboard doesn't change.
Is there something wrong with the system?

No. Leaderboard is frozen from 17:30(JST).

What is chained rings definition?

Supposing that the circles are physical objects, two rings are considered to be chained if we cannot separate them in the arbitrary distance.

> Can C have leading zeros?
> The input has no leading zeros.
C = 0 has a leading zero. Is it possible that C = 0?

The input has no extra leading zeros to be exact.
It is possible that C = 0

How long is the decimal of an input? 

At most 8 digits after the decimal point.

Can I remove a server clock from the web site?
It disturbs printing.

We hid the server clock of problem pages.

Can C have leading zeros?

The input has no leading zeros.

Will the problem statements be given to us as a PDF file?

The problem statements will be given on this website only.