Every single one of them. Stacked from floor to ceiling, roof to rafter. Each container containing exactly 420 children without exception.
612 containers times 420 = 257,040 children.
Check my math.
As always, bumpkin, you have your finger on the pulse of Q world.
I'll have you crappin' Q's yet. (see what you can do with that line).

Sad and sorry logistical planning.
20 foot containers? 40? 45? High-cap or no?
What separation table applies for these live cargo
containers and those required to be isolated per IMO regulations?
Refrigerated? Ventilated? What power source? Propane,
diesel or ship's electrical? Otherwise what provision for
live cargo... water, food, sanitary, drainage?
Sorry, but you've shuffled into one of the three things in the
world that I'm actually an expert at.
There ain't no live kids in any container on any ship
without many many special and obvious maintenance operations
going on.