
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
Xiao Ming noticed when climbing stairs: if there is only one step, there is one way to climb it. If there are two steps, he can climb one step at a time, or two steps in one go, making a total of two ways. Given that he can only climb one or two steps at a time, following the above pattern, there are three ways to climb three steps. So, how many ways are there to climb four steps?

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