
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Fiona has a collection of 4 unique marbles: a Ruby, an Emerald, a Sapphire, and a Diamond. She wants to display them in a row on her shelf, but she does not want the Sapphire and the Diamond, or the Ruby and the Emerald to be next to each other. Calculate the number of valid arrangements Fiona can create.

Present the answer in LaTex format: \boxed{Your answer}
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