If another list number is full, how to limit the move to it and trigger function?

For example, there are three ul, each UL can only have 10 li. If you drag onto the maximum number of regions, it will be fail and trigger function nextpage();
```
#1:

#2:

.....10 li....

#3:

#1 or #3 cannot drag to #2 .
If #2 has been moving to #1, #1 reached 10, #2 can no longer move to #1
```
What should I do to achieve this effect?
Thank you!