my $href; @{ $href }{ 'a' .. 'z' } = 1 .. 26;
my @required_fields = qw[ a c e g i k m o q s u w y ];
for my $k ( \( @h{ @required_fields } ) ){ 
    print $$k; 
}
1
3
5
7
9
11
13
15
17
19
21
23
25

##</code><code>##

while( my( $kref, $vref ) = \( each %{ $href } ) ) { 
    print $$kref, ' => ', $$vref; 
}