use strict;

my $names = " John 20, Bill 34, Jane 28, Wall 18, Tom 19";
print $names,"\n";

my %hash_list = sort(split (/,/, $names));
print %hash_list,"\n";

my @keys = sort {
                    $hash_list{$a} cmp $hash_list{$b}
            } keys %hash_list; 

print %hash_list, "\n";
print @keys, "\n";