Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| AIRLINE | ICAO | IATA | CALLSIGN | COMMENCED\nOPERATIONS |
| --- | --- | --- | --- | --- |
| Air Uganda | UGA | U7 | UGANDA | 2007 |
| Eagle Air (Uganda) | EGU | H7 | AFRICAN EAGLE | 1994 |
| Fly540 Uganda | FUL |  | ORANGE CRANE | 2008 |
| Pearl Air Services | PBY |  | PEARL SERVICES |  |
| Royal Daisy Airlines | KDR | 6D | DARLINES | 2005 |
| Skyjet Airlines | SJU | UQ | SKYJET | 2003 |
| Africa Safari Air | ASA | AS | ASA | 2013 |
| Uganda Air Cargo | UCC |  | UGANDA CARGO | 1994 |
| United Airlines Limited |  |  |  |  |
Question:
what number of airlines use the first letter of their name in their icao?
Answer:
6