user: Question: How many times did Silas leave as a team manager?
Columns: ['Team', 'Outgoing manager', 'Manner of departure', 'Date of vacancy', 'Position in table', 'Replaced by', 'Date of appointment']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Santos', 'Adílson Batista', 'Sacked', 'February 27', 'Pre-season', 'Muricy Ramalho', 'April 8']
SQL:

assistant: SELECT COUNT("Manner of departure") FROM "Table" WHERE "Outgoing manager" = 'Silas';