Write a program whose inputs are four integers, and whose outputs are the maximum and the minimum of the four values. For example, if the input is 12, 18, 4, 9, the output is "Maximum is 18" and "Minimum is 4".
The program must define and call the following two functions. Define a function named "max_number" that takes four integer parameters and returns an integer representing the maximum of the four integers. Define a function named "min_number" that takes four integer parameters and returns an integer representing the minimum of the four integers.
Note: DO NOT use "max" and "min" as function names.