A bus ticket is called 'lucky', if in its number, which consists of 2n digits (the number may have leading zeros), the sum of the first n digits equals the sum of the last n digits. A passenger wants to certainly ride with a lucky ticket. He buys a ticket, checks its number, and then, if necessary, buys a few more tickets with successive numbers. How many additional tickets will the passenger have to buy, having spent the minimum sum of money?
1 <= n <= 10
The input file contains a line of 2n digits, which may have several leading zeroes - the number of the first ticket.
Process to the end of file.
The output file must contain a number - the amount of the additionally bought tickets.