Each of the letters $W$, $X$, $Y$, and $Z$ represents a different integer in the set $\{ 1,2,3,4\}$, but not necessarily in that order. If $\dfrac{W}{X} - \dfrac{Y}{Z}=1$, then what is the sum of $W$ and $Y$?

Let's think step by step and output the final answer within \boxed{}.
user