```
//质数的性质

include [HTML_REMOVED]

int main()
{
int n;
std::cin>>n;
while(n–)
{
int x,flag =1;
std::cin>>x;

    if( x % 6 !=1 && x % 6 != 5)    
    {   
        flag = 0;
    }
    for(int j =5;j * j<x;j += 6)
    {

        if(x % j ==0 || x % (j+2) == 0)     flag = 0;
    }
    if(x <=3) flag=1;

    if(flag == 1) printf("%d is prime\n",x);
    if(flag == 0) printf("%d is not prime\n",x);
}
return 0;

}
````