let f$($x$)=$ square root $-$x if x $<0,3-$x if $0<$ or equal to x which is $<$ to $3,(3-$x$)^2$ if x $>3,$ Evaluate each limit$,$ if it exists.

a$)$ the limit as x approaches $0^+$ f$($x$)$

b$)$ The limit as x approaches $0^-$ f$($x$)$