What are the possible output sequences from the following program?

Choose all the possible output sequences. Negative partial scores will be given if incorrect answers are chosen.

int main$()\{$

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

printf$("$Y$")$;

exit$(0)$;

$\}$else$()\{$

printf$("$z$")$;

waitpid$(-1,$NULL,$0)$;

$\}$

printf$("$x$")$;

exit $0$;

$\}$