user: Question: What is the lowest of  Episode Number that has a Air Date on 20 July 2007?
Columns: ['Episode Number', 'Air Date', 'Guest Host', 'Musical Guest (Song performed)', '"Coat of Cash" Wearing Celebrity']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, '1 June 2007', 'David Walliams', 'Mutya Buena ( Real Girl )', 'Pete Bennett']
SQL:

assistant: SELECT MIN("Episode Number") FROM "Table" WHERE "Air Date" = '20 July 2007';