Write a function that calculates the maximum common divisor (MCD) of two positive integers, according to the following Euclids algorithm. Assume the integers a and b, when a > b. If b divides a precisely, this is the MCD. If the remainder r of the division a/b is not 0, then we divide b with r. If the new remainder of the division is 0, then the MCD is r; otherwise, this procedure is repeated. Write a C program that reads two positive integers and uses the function to calculate their MCD.