////  1459 Prime ring problem.cpp//  Jobdu////  Created by PengFei_Zheng on 23/04/2017.//  Copyright © 2017 PengFei_Zheng. All rights reserved.// #include <stdio.h>#include <iostream>#include <algorithm>#include <string.h>#include <cmath>#define PRIME 13#define MAX_SIZE 21using namespace std; int n;int ans[MAX_SIZE];bool used[MAX_SIZE]; int prime[]={2,3,5,7,11,13,17,19,23,29,31,37,41};bool judge(int x){    for(int i = 0 ; i < PRIME ; i++){        if(prime[i]==x)            return true;    }    return false;} void check(){    if(!judge(ans[n]+ans[1])) return;    for(int i = 1 ; i <= n ; i++){        if(i!=1) printf(" ");        printf("%d",ans[i]);    }    printf("\n");} void DFS(int num){    if(num>1){        if(!judge(ans[num] + ans[num - 1])) return;    }    if(num==n){        check();        return;    }    for(int i = 2 ; i <= n ; i++){        if(!used[i]){            used[i] = true;            ans[num+1] = i;            DFS(num+1);            used[i] = false;        }    }} int main(){    int kase = 0;    while(scanf("%d",&n)!=EOF){        kase++;        memset(used,false,sizeof(used));        ans[1] = 1;        used[1]=true;        printf("Case %d:\n",kase);        DFS(1);        printf("\n");    }    return 0;}/**************************************************************    Problem: 1459    User: zpfbuaa    Language: C++    Result: Accepted    Time:590 ms    Memory:1520 kb****************************************************************/