
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
The function $f(x)$ is an even function defined on $\mathbb{R}$ with a period of 2. If $f(x)$ is a decreasing function on the interval [-1, 0], then on the interval [6, 8], $f(x)$ is _____. (① increasing ② decreasing ③ first increasing then decreasing ④ first decreasing then increasing ⑤ constant function. Fill in the blank with the appropriate number(s) based on the conditions given in the problem.)

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