How do you know if your chick has pasty butt?

[My 3 Babies]

I am a little concerned...
I have 3 little chicks and I am not quite sure how to tell apart the cord and pasty butt.

Please help

 

[ten chicks]

I am a little concerned...
I have 3 little chicks and I am not quite sure how to tell apart the cord and pasty butt.

Please help

In pasty butt,poop is stuck to/over the vent. Umbilical cord is lower,beneath vent area. If umbilical is still attached,don't pull,will dry and fall off.