In java

The following checksum formula is widely used by banks and credit card companies to validate legal account numbers:

d0+f(d1)+d2+f(d3)+d4+f(d5)+...=0(mod 10)

The "di" are the decimal digits of the account number and f(d) is the sum of the decimal digits of 2d (for example, f(7)= 5 because 2*7=14 and 1+4=5). For example, 17,327 is valid because 1+5+3+4+7=20, which is a multiple of 10. Implement the function f and write a program to take a 10-digit integer as a command-line argument and print a valid 11-digit number with the given integer as its first 10 digits and the checksum as the last digit.