user: Question: How many parties are there in races involving Dawson Mathis?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Georgia 1', 'Ronald "Bo" Ginn', 'Democratic', 1972.0, 'Re-elected', 'Ronald "Bo" Ginn (D) Unopposed']
SQL:

assistant: SELECT COUNT("Party") FROM "Table" WHERE "Incumbent" = 'Dawson Mathis';