Physical Flux

A point charge $q$ is placed on the line $AH$ and just outside the cube (of side $d$ ) at a distance of $r$ $(r << d)$ .

Total flux of electric field through the surface $ABCD$ is $\large\ \frac {q}{A{ \varepsilon }_{ 0 }}$ , where $A$ is an integer.

Find the absolute value of $A$ .