
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 triangle of numbers is constructed as follows. The first row consists of the numbers from  $1$  to  $2000$  in increasing order, and under any two consecutive numbers their sum is written. (See the example corresponding to  $5$  instead of  $2000$  below.) What is the number in the lowermost row?

1 2 3 4 5
  3 5 7 9
   8 12 16
    20 28
       4

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