user: Question: how many new managers replaced  manager(s) who Resigned? 
Columns: ['Team', 'Outgoing manager', 'Manner of departure', 'Date of vacancy', 'Incoming manager', 'Date of appointment']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Warri Wolves', 'Lawrence Akpokona', 'fired', 'end of 2009-10 season', 'Paul Aigbogun', '2 September 2010']
SQL:

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