
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
Two brothers sold a flock of sheep that belonged to both of them, receiving as many rubles for each sheep as there were sheep in the flock. The brothers divided the money received as follows: first the elder brother took ten rubles from the total amount, then the second brother took ten rubles, after which the first brother took another ten rubles, and so on. The younger brother lacked ten rubles in the end, so he took all the remaining small change, and in addition, to make the division fair, the elder brother gave the younger brother his pocket knife. What was the value of the pocket knife?

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