
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 positive integer \( n \geqslant 2 \). Suppose integers \( a_{0}, a_{1}, \cdots, a_{n} \) satisfy \( 0 = a_{0} < a_{1} < \cdots < a_{n} = 2n-1 \). Find the minimum possible number of elements in the set \(\{a_{i} + a_{j} \mid 0 \leqslant i \leqslant j \leqslant n\}\).

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