Prime Ring Problem

A ring is composed of n (even number) circles as shown in diagram. Put natural numbers 1, 2, . . . , n into each circle separately, and the sum of numbers in two adjacent circles should be a prime. Note: the number of first circle should always be 1. Input n (0 < n ≤ 16) Output The output format is shown as sample below. Each row represents a series of circle numbers in the ring beginning from 1 clockwisely and anticlockwisely. The order of numbers must satisfy the above requirements. You are to write a program that completes above process. Sample Input 6 8 Sample Output Case 1: 143256 165234 Case 2: 12385674 12583476 14765832 16743852