i need help on this

i need a pseudo code preferable in php that does the below function

moves the next person in line to another level upon an addition of 12

To put it in a broader view

Users get in into the system

Each user qualifies to level 2 after bringing 3 down lines

Each level 2 user needs 12 more level 2 user to move on to level 3

The system fix the 12 level 2 users under the first level 2 user so as to move into level 3

The same process is repeated to the subsequent level 2 users after the first level 2 user is moved to level 3 by the reason of the 12 level 2 acquired as down lines

Each user next inline to the first level 2 user needs 12 more level 2 users to move to level 3

So, basically

The first level 2 user moves to level 3 when there are 13 level 2 users in the system

The second moves when there are 25 level 2

And the progression goes on with an addition of 12 for any level 2 moving to level 3

What we need again is an algo

And probably a pseudo code to work with