GCD Program

1.	The greatest common divider (GCD) of two Integers is the largest Integer that evenly divides each of the two numbers.
2.	Write a procedure, named GCD, that returns the greatest common divider of two Integers.
3.	Incorporate the procedure into a program that reads two values from the user.
4.	Write a recursive version of the GCD procedure. The GCD of x and y is defined recursively as follows:
4.1	If y is equal to 0, then GCD(x,y) is x; otherwise, GCD(x,y) is GCD(y,x Mod y), where Mod is the modulus operator.