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 10·0 + 9·2 + 8·0 + 7·1 + 6·3 + 5·1 +4·4 +3·5 + 2·2 + 1·x 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.