Square full number

A number $n$ is called squarefull if $p^2$ divides $n$ for each prime factor $p$ of $n$ .

Given $n$ is a squarefull number and its square root is not an integer. If it can always be expressed in the form $a^x$ $b^y$

where $a$ , $b$ , $x$ and $y$ are all positive integers greater than $1$ ,

then find the value of $x+y$ .