$s="102119200001141520080518001605181200080103110518"; 
while($p=substr($s,$i,2)){
	$i+=2;$a="a";
	$p--; 
	while($p){
		if($p<0){
			$a="";
			last;
		}
		$p--;
		$a++;
	} 
	print uc($a);
}
print "\n";