
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
Bill is sent to a donut shop to purchase exactly seven donuts. The shop offers four different kinds of donuts, and Bill must buy at least one of each kind. How many different combinations of donuts can Bill purchase?

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