$(10\%)$ Consider the function func as shown below, where the two lists list $1$ and list $2$ are both ordered in ascending order.

struct item

$\{$

int value;

struct item $*$next;

$\}$;

int func $($struct item $*$list$1,$ struct item $*$list$2)$

$\{$

struct item $*$ptr$1,*$ptr$2$;

int count $=0$;

ptr$1=$ list $1$ ;

ptr$2=$ list$2$;

while $(($ptrl $!=$ NULL$)$ &&&$($ptr$2$ NULL$))$

$\{$

if $($ptrl$->$value $$ ptr$2->$value$)$

ptrl $=$ ptrl $$ next;

else if $($ptrl$->$value $>$ ptrz$->$value$)$

ptr $2=$ ptr $2$ next

else

$\{$

ptr $1=$ ptr $1$ next ;

ptr$2=$ ptr $2$ next ;

$\}$

count $++$;

$\}$

return count;

$\}$

If $m$ and $n$ are the number of items in list $1$ and list $2$ respectively, what is the worstcase time complexity of func$($list $1,$ list $2)?$