int main$()\{$

int x $=1$;

int i;

for $($i $=0$; i $<2$; i$++)\{$

if $($fork$()==0)\{$

$//$ block $1$

x$++$;

printf$("$loop $\%$d$,$ x$=\%$d

$",$ i$,$ x$)$;

$\}$ else $\{$

$//$ block $2$

x$--$;

printf$("$loop $\%$d$,$ x$=\%$d

$",$ i$,$ x$)$;

$\}$

$\}$

return $0$;

$\}$Directly running this piece of code may produce different outputs every time.

Briefly explain why.