user: Question:  how many first elected with incumbent being William C. Lantaff
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Florida 2', 'Charles Edward Bennett', 'Democratic', 1948.0, 'Re-elected', 'Charles Edward Bennett (D) Unopposed']
SQL:

assistant: SELECT COUNT("First elected") FROM "Table" WHERE "Incumbent" = 'William C. Lantaff';