What is the position of john charles?
{'header': ['Overall Pick #', 'AFL Team', 'Player', 'Position', 'College'], 'page_title': '1967 American Football League Draft', 'page_id': '', 'types': ['real', 'text', 'text', 'text', 'text'], 'id': '1-12165135-1', 'section_title': 'Round one', 'caption': 'Round one', 'rows': [['4', 'Miami Dolphins', 'Bob Griese', 'Quarterback', 'Purdue'], ['5', 'Houston Oilers', 'George Webster 1', 'Linebacker', 'Michigan State'], ['6', 'Denver Broncos', 'Floyd Little', 'Running Back', 'Syracuse'], ['12', 'New York Jets', 'Paul Seiler', 'Offensive Guard', 'Notre Dame'], ['14', 'San Diego Chargers', 'Ron Billingsley', 'Defensive Tackle', 'Wyoming'], ['17', 'Oakland Raiders', 'Gene Upshaw', 'Offensive Guard', 'Texas A&I'], ['21', 'Boston Patriots', 'John Charles', 'Defensive Back', 'Purdue'], ['22', 'Buffalo Bills', 'George Daney', 'Offensive Guard', 'Arizona State'], ['23', 'Houston Oilers', 'Tom Regner', 'Offensive Guard', 'Notre Dame']], 'name': 'table_12165135_1'}