user: Question: What is the greatest height (cm) that has a 1983-1984 team of montreal canadiens, with a jersey less than 21?
Columns: ['Position', 'Jersey #', 'Name', 'Height (cm)', 'Weight (kg)', 'Birthdate', 'Birthplace', '1983–1984 Team']
Types: ['text', 'real', 'text', 'real', 'real', 'text', 'text', 'text']
Sample row: ['G', 31.0, 'Tom Barrasso', 190.0, 95.0, 'March 31, 1965', 'Boston, Massachusetts', 'Buffalo Sabres']
SQL:

assistant: SELECT MAX("Height (cm)") FROM "Table" WHERE "1983–1984 Team" = 'montreal canadiens' AND "Jersey #" < 21.0;