Suppose, there are n objects and you are given the option to choose r objects from them. If the order of choice matters, it is called Permutation. Otherwise, it is known as Combination. Given the values of n and r, the number of permutations, P(n, r) and combinations, C(n,r) are determined using the following formula: n! P(n,r): (n-r)! n! C(n,r) r! (n r)! where,n! = 1x2 x3xx (n-1) xn Write a program that takes n and r as input and calculates the corresponding number of permutations and combinations. n and r should be non-negative integers and nr. If user gives illegal inputs, your code should print a proper error message. You are required to write a user- defined function to calculate the factorial. Call the function from main function to properly calculate the permutation and combination values. For this problem, recursion is not necessary.