Question 20A sequence $x_0,x_1,x_2,x_3,\ldots$ of integers satisfies the following conditions: $x_0=1$, and for any positive integer $n\ge1$, $|x_n-1|=|x_{n-1}+2|$. Find the maximum possible value of $2019-(x_1+x_2+\cdots+x_{2018})$.