Change at the Ticket Booth

A ticket booth sells rides for 5 dollars each. Customers queue up and pay one at a time, each with a single 5, 10 or 20 dollar bill. The booth opens with an empty cash drawer and can only give change from the bills it has collected so far.

Write can_give_change(bills) that returns True if every customer, in order, can get the correct change, and False as soon as one cannot.

Examples

can_give_change([5, 5, 5, 10, 20])   # returns True
can_give_change([5, 5, 10, 10, 20])  # returns False
can_give_change([10, 5])             # returns False

In the second example each 10 takes a 5 as change, so when the 20 arrives the drawer holds two 10s and no 5s: there is no way to make 15.

Constraints

• 0 <= len(bills) <= 10000
• Every bill is 5, 10 or 20