user: Question: How many different values if the number is high rebounds can be found for the game on March 13?
Columns: ['Game', 'Date', 'Team', 'Score', 'High points', 'High rebounds', 'High assists', 'Location Attendance', 'Record']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [53.0, 'March 2', '@ Portland', 'L 97–102', 'Charles Barkley , Dan Majerle (20)', 'Charles Barkley (12)', 'Dan Majerle (7)', 'Memorial Coliseum 12,888', '40–13']
SQL:

assistant: SELECT COUNT("High rebounds") FROM "Table" WHERE "Date" = 'March 13';