Hello I need help understanding BLP system

Consider a BLP system with the following clearances (classifications) and category sets:

-3 clearances/classification: U S TS

-3 category sets: {ASIA, EUR, US}, {EUR, US}, {US}

(do not consider other unlisted category sets, like {ASIA} or {EUR}. They won't appear in the system)

Questions: The two conditions of BLP can be summarized as "read down" (a subject s can read an object o if and only if s dominates o) and "write up" (a subject s can write an object o if and only if o dominates s). Explain why "no read up" and "no write down" are insufficient to describe BLP (hind what levels Alice cannot read).