user: Question: How many incumbents are there in Pennsylvania 5?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Pennsylvania 1', 'Robert Waln', 'Federalist', '1798 (Special)', 'Retired Democratic-Republican gain', 'William Jones (DR) 50.2% Francis Gurney (F) 49.8%']
SQL:

assistant: SELECT COUNT("Incumbent") FROM "Table" WHERE "District" = 'Pennsylvania 5';