
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
What is the smallest sum of two $3$-digit numbers that can be obtained by placing each of the six digits $1, 2, 3, 4, 5, 6$ in one of the six boxes in the addition problem, where each digit is used exactly once?
A) 381
B) 392
C) 403
D) 414 
E) 425

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