user: ### NOW ANSWER:
Question: What year was incumbent Mark W. Hannaford elected?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['California 4', 'Robert L. Leggett', 'Democratic', 1962.0, 'Re-elected', 'Robert L. Leggett (D) 50.2% Albert Dehr (R) 49.8%']
SQL:

assistant: SELECT MIN("First elected") FROM "Table" WHERE "Incumbent" = 'Mark W. Hannaford';