@keys = keys{%hash};
foreach $key (@keys)
{
   $value = $hash{$key};    # notice $ versus % here
   push(@values, $value);
}
sort(@values);
print "@values\n";

##</code><code>##

Can't use subscript on private hash at foo.pl line 123, near "$key}"
(Did you mean $ or @ instead of %?)
BEGIN not safe after errors--compilation aborted at foo.pl line 123.