杭电1016（dfs）增所广收

A ring is compose of n circles as shown in diagram. Put natural number 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 < 20).

 

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. Print solutions in lexicographical order.You are to write a program that completes above process.Print a blank line after each case.

 

Sample Input

6
8

 

Sample Output

Case 1: 1 4 3 2 5 6 1 6 5 2 3 4 Case 2: 1 2 3 8 5 6 7 4 1 2 5 8 3 4 7 6 1 4 7 6 5 8 3 2 1 6 7 4 3 8 5 2

一个环，相邻两个数之和是素数，，并且把所以可能都按顺序输出来。 

#include 
#include 
using namespace std;
#define max 21
int vis[max],hk[max];
int n,k=1;
bool ls(int a,int b)
{
	int c=a+b;
	for(int i=2;i*i<=c;i++)
	{
		if(c%i==0)
			return false;
	}
	return true;
}
void DFS(int a)
{
	if(n==a&&ls(1,hk[n-1]))
	{
		cout<>n)
	{
		cout<<"Case "<