manage the cash register

Your program has currencies of Rs. 1, 5, 10, 20, 100, 500, 2000.
Your user enters a bill amount say Rs. 243.
Your user then enters a cash given say Rs. 2000.
Now, help the user by telling how can he/she return the change to the customer with minimum number of notes?

bonus

You need two inputs from the user. Can you make it in a way where second input is only visible after the first input is given i.e. bill amount should be filled.