
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
A number \( A \) consisting of eight non-zero digits is added to a seven-digit number consisting of identical digits, resulting in an eight-digit number \( B \). It turns out that \( B \) can be obtained by permuting some of the digits of \( A \). What digit can \( A \) start with if the last digit of \( B \) is 5?

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