
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
Among the following events:  
① For any real number $x$, $x^2<0$;  
② The sum of the interior angles of a triangle is $180^\circ$;  
③ Riding a bike to a crossroad and encountering a red light;  
④ Someone winning a lottery ticket;  
The events that are random are __________.

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