
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
A stack of books has 15 books on the bottom shelf, and one less book in each successive shelf, ending with four books on the top shelf. How many books are in total on the shelves?

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