Programming challenge description:The Cartesian product of two lists of numbers A and B is defined to be the set of all points (a, b) where a belongs in A and b belongs in B. It is usually denoted as A x B, and is called the Cartesian product since it originated in Descartes' formulation of analytic geometry. Given two sets of real numbers, their Cartesian product comes in form of ordered pairs. e.g. A = [1, 2, 3]B = [4, 5]Cartesian product is C = [(1, 4), (1, 5), (2,4), (2.5), (3,4), (3,5)]Now given a coordinate tuple (i, j), where i indicates A[i] and j indicates B[j], with A, B known, implement a function that returns the index of a member in Cartesian product C according to (i, j)Starter code:public class Main {/*** Iterate through each line of input.*/public static void main(String[] args) throws IOException {InputStreamReader reader = new InputStreamReader(System. in, StandardCharsets. UTF_8);BufferedReader in = new BufferedReader(reader);String line;while ((line = in. readLine()) != null) {System. out. println(line);}}}