At a lemonade stand, each lemonade costs $5. Customers are standing in a queue to buy from you and order one at a time. Each customer pays with either a $5, $10, or $20 bill. You must provide the correct change to each customer. You start with no change on hand.

Given an integer array bills where bills[i] is the bill the i-th customer pays, return true if you can provide every customer with correct change, or false otherwise.