What city does the business came from where they received a high volume of check-ins from 12 am to 1 am on Saturday.
12 am refers to opening_time = '12AM'; 1 am refers to closing_time = '1AM'; on Saturday refers to day_of_week = 'Saturday'
SELECT T1.city FROM Business AS T1 INNER JOIN Business_Hours AS T2 ON T1.business_id = T2.business_id INNER JOIN Days AS T3 ON T2.day_id = T3.day_id WHERE T2.closing_time = '1AM' AND T2.opening_time = '12AM' AND T3.day_of_week = 'Saturday'