
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
Let $N$ be a positive multiple of $5$. One red ball, one blue ball, and $N$ green balls are arranged in a line in random order with the condition that the red and blue balls must be adjacent. Let $P(N)$ be the probability that at least $\tfrac{3}{5}$ of the green balls are either entirely on the left or the right of the pair of red and blue balls. What is the sum of the digits of the least value of $N$ such that $P(N) < \tfrac{321}{400}$?
A) 12
B) 13
C) 14
D) 15
E) 16

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