
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
Given a line $l$ passes through points $A(2, a)$ and $B(a, -1)$, and is parallel to the line $m: 2x-y+2=0$.

(Ⅰ) Find the equation of line $l$;  
(Ⅱ) A line passing through point $A$ and perpendicular to $l$ intersects line $m$ at point $C$. Find the length of segment $BC$.

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