
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 frog starts at the point (2, 1) on a coordinate plane and makes jumps of length 1 unit parallel to the coordinate axes. Each jump's direction (up, down, left, right) is chosen randomly. The sequence of jumps ends when the frog lands on any side of the square defined by vertices (0, 0), (0, 4), (4, 4) and (4, 0). Find the probability that the sequence ends on a vertical side (either x = 0 or x = 4) of the square.

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