Checksum. The International Standard Book Number (ISBN) is a 10-digit code that uniquely specifies a book. The rightmost digit is a checksum digit that can be uniquely determined from the other 9...

Checksum. The International Standard Book Number (ISBN) is a 10-digit code that uniquely specifies a book. The rightmost digit is a checksum digit that can be uniquely determined from the other 9 digits, from the condition that d₁
+ 2d₂
+3d₃
+ ... + 10d10 must be a multiple of 11 (here di denotes the ith digit from the right). The checksum digit d1 can be any value from 0 to 10. The ISBN convention is to use the character 'X' to denote 10. As an example, the checksum digit corresponding to 020131452 is 5 since 5 is the only value of x between 0 and 10 for which

is a multiple of 11. Write a program that takes a 9-digit integer as a command-line argument, computes the checksum, and prints the ISBN number.