a quick and dirty solution is to convert the array to string using unique separator like '###' for example
in php this means :
//on page 1
$county = join('###', $conty);
// transfer it to page 3 via hidden filelds and there :
$county = implode('###', $conty);
p.s. i would use POST instead of GET
pay attention and to [man]serialize [/man] and [man]unserialize [/man] functions
they can also be useful in similar situations