Solve for C please

One common way of verifying if the data integrity of a file was preserved during a copy or transmission is to verify if the checksum matches. The checksum is a small piece of data computed from the original data. Your task is to compute a recursive function that maps an integer into a single digit to be used as checksum. Given an input integer in the range from 0 to 1012, the checksum is the sum of the digits of the input number. While the resulting sum has multiple digits, the checksum will be the sum of its digits instead. For instance: - if the input is 34 , the checksum is 7(3+4); - if the input is 99 , the sum of its digits is 18(9+9), so the checksum is 9(1+8); - if the input is 99999999999 , the sum of its digits is 99(9+9+9+9+9+9+9+9+9+9+9), whose sum of digits is 18 (9+9), so the checksum is 9(1+8). Requirements 1. Follow the format of the examples below. 2. Make sure your variables and parameters have the correct data types. 3. You must implement a recursive function to compute the checksum. This function can have only one parameter. 4. You are not allowed to use for, while, and do/while in your solution. Examples (your program must follow this format precisely) Example \#1 Input: 34 Checksum: 7 Example \#2 Input: 99 Checksum: 9