user: Question: What is the total number of weeks that the buffalo bills played against the San Diego Chargers?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 10, 1967', 'New York Jets', 'W 20–17', '45,748']
SQL:

assistant: SELECT SUM("Week") FROM "Table" WHERE "Opponent" = 'San Diego Chargers';