C program very urgent please

ISBN-13 is a standard for identifying books. It uses 13 digits ISBN-13 Formatd2d2d3d4d5d6d2d3d9d10d11d12d13 Example 9 7 8 0 1 3 2 1 3 0 8 0 6 The last digit d13 is a checksum, which is calculated from the other digits using the following formula: 10 - (d1 + 3d2+d3 + 3d4 +d5 + 3do + d7 + 3dg + d9 + 3d 10 + d11 + 3d12)%10 If the checksum is 10, replace it with 0. 1. Write a function named readString that takes only an array of character as parameter named data, reads a string of size 13 from the user, and sore it the array data. The function should ask the user to enter a proper string of until the user enters a string of size 13 2. Write a function named checksum that takes only one input parameters str of type char* (null-terminated C strings of characters) and calculates and returns the check sum from the first 12 digits 3. Write the main function that Prints your full name and Student ID Define a proper variable to store a c-string Properly call the function readString to read a 13-digit ISBN Displays valid ISBN if the digit 13 equals the checksum calculated in part2 or invalid otherwise