
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
Let set $A=\{1,2,3,4\}$, and set $B=\{-1,-2\}$. Suppose there is a mapping $f: A \rightarrow B$ and every element in set $B$ is an image of an element in $A$ under the mapping $f$. Calculate the number of such mappings $f$.

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