make functions for each ads,and call those ads function(country based);
like:

if ( $CountryCode == RS || $CountryCode == ME ) {
functionnameRSorME;

}

else if ( $CountryCode == HR || $CountryCode == BA ) {
functionnameHR;

}

else if ( $CountryCode == DE || $CountryCode == AU || $CountryCode == CH ) {
functionnameRSorME;
}

else {
functionname;

}

and add those ads in functions.if its not cleared to you,then maybe i can help but later.