
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
Neznaika named four numbers, and Ponychik wrote down all their pairwise sums on six cards. Then he lost one card, and the remaining cards had the numbers \(270, 360, 390, 500, 620\). What number did Ponychik write on the lost card?

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