88. Given that $x, y, z$ are three distinct non-zero natural numbers, if
$$
\overline{x y y y y}+\overline{x y y y}+\overline{x y y}+\overline{x y}+y=\overline{y y y y z} .
$$

where $\overline{x y y y y}$ and $\overline{y y y y z}$ are both five-digit numbers, when $x+y$ is maximized, the corresponding value of $x+y+z$ is
Reference answer: 22