Figure below$($reproduced below for ready reference$)$ is a $4-$bit circuit that can add or subtract numbers $($positive numbers in true form; negative numbers in complement form$).$ If the inputs are as follows, what is the output? the figure uses XNOR gate look carefly into figure.

$Ad\frac{d}{S}$ubt $=1$;$A=1011$;$B=1010$

$Ad\frac{d}{S}$ubt $=1$

$A=1011$

$B=1010$