The given expression can be simplified as follows:

2018 + 2016 + 2014 + ... + 2 - 2015 - 2013 - 2011 - ... - 1

Grouping the positive terms and the negative terms separately:

(2018 + 2016 + 2014 + ... + 2) - (2015 + 2013 + 2011 + ... + 1)

The positive terms form an arithmetic series with a common difference of 2 and the first term being 2018. We can use the formula for the sum of an arithmetic series to find their sum:

Sum of positive terms = (n/2)(first term + last term)
= (n/2)(2018 + 2)
= (n/2)(2020)
= 1010n

The negative terms also form an arithmetic series with a common difference of 2 and the first term being 2015. Using the same formula, we can find their sum:

Sum of negative terms = (n/2)(first term + last term)
= (n/2)(2015 + 1)
= (n/2)(2016)
= 1008n

Substituting these sums back into the original expression:

1010n - 1008n

Simplifying further:

2n

Therefore, the given expression simplifies to 2n.