my @cityKeys;
my @distanceKeys;

foreach( @cgiParamKeys ) {
  if( /city/ ) {  #If a hidden city field found store it in an array;
    push @cityKeys, $_; #Store the field in an array
    @cityKeys = sort @cityKeys;   #Sort the array
  }
  if( /distance/ ) { #If a hidden distance field found, store it in an array
    push @distanceKeys, $_; #Store it in the array
    @distanceKeys = sort @distanceKeys;  #Sort the array
  }
}

##</code><code>##

my @cityKeys     = sort grep { /city/     } @cgiParamKeys;
my @distanceKeys = sort grep { /distance/ } @cgiParamKeys;

##</code><code>##

foreach (@cityKeys, @distanceKeys)

##</code><code>##

if (/city/ || /distance/)

##</code><code>##

foreach  (@cityKeys, @distanceKeys) {
  print $cgi->hidden($_ => $cgiParam{$_});
}