tie my %myhash, 'Tie::IxHash';

%myhash = ( 'ne', undef, 
            'na', undef,
            'e', undef, 
            'a', undef, 
            'z', undef, 
            'h', undef,
             2, undef,
             5, undef, 
            12, undef,  
             7, undef);
print Dumper(\%myhash);