
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
Find the smallest positive integer that cannot be expressed in the form  $\frac{2^a - 2^b}{2^c - 2^d}$ , where  $a$ ,  $ b$ ,  $c$ ,  $d$  are non-negative integers. 


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