Prime Ring Problem

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <vector>
using namespace std;

int n;
int vis[25];
int prime[38]={0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1};
int ans[25];

void print(int m)
{
int i;
printf("%d",ans[1]);
for(i=2;i<=n;i++)
{
printf(" %d",ans[i]);
}
printf("\n");
}

void dfs(int point)
{
if(point==n && prime[ans[point]+ans[1]])
{
print(point);
}
else
{
for(int j=2;j<=n;j++)
{
if(!vis[j]&& prime[ans[point]+j])
{
ans[point+1]=j;
vis[j]=1;
dfs(point+1);
vis[j]=0;
}
}
}
}

int main()
{
int cas=0;
while(scanf("%d",&n)!=EOF)
{
cas++;
memset(vis,0,sizeof(vis));
vis[1]=1;
ans[1]=1;
printf("Case %d:\n",cas);
dfs(1);
printf("\n");
}
}