3. Grupul de litere incepe cu:

IS-15-A??IS-15-B??IS-15-C??IS-15-D??IS-15-E??IS-15-F??IS-15-G??IS-15-H??IS-15-I??
IS-15-J??IS-15-K??IS-15-L??IS-15-M??IS-15-N??IS-15-O??IS-15-P??IS-15-Q??IS-15-R??
IS-15-S??IS-15-T??IS-15-U??IS-15-V??IS-15-W??IS-15-X??IS-15-Y??IS-15-Z??