sub print_lineage {
    my ($x) = @_;
    my @p;
    while (exists $kids{$x}) {
	$x = $kids{$x};
	push @p,$x;
    }
    if (@p) {
	local ($") = ", ";
	print "Lineage of $_[0] is @p\n";
    } else {
	print "Lineage of $_[0] is unknown\n";
    }
}
print_lineage $_ for @ARGV;