30s
How does rank hierarchy go?

From most inferior to the most superior!

A

E-1 - E-9 → O-1 - O-10

B

E-9 - E-1 → O-10 - O-1

C

O-10 - O-1 → E-9 - E-1

D

O-1 - O-10 → E-1 - E-9