What does "Crash!!!ACCESS_VIOLATION" mean??
Why this problem happen??? How to settle it??? Thanks!!!
Source code:
#include<iostream.h>
unsigned long int  is_prime(unsigned long int  x)
{
    unsigned long int  mid=x/2+1,y;
    for(y=2;y<mid;y++)
    {
        if(x%y==0)return 0;
    }
    return 1;
}
unsigned long int  prime_k(unsigned long int  k)
{
    unsigned long int  count,l;
    for(l=2,count=0;count<k;)
    {
        if(is_prime(l))
        {
            count++;
            l++;
        }
        else l++;
    }
    l--;
    return l;
}
int main()
{
    unsigned long int  num,a[100],i,prime,m;
    cin>>num;
    for(i=0;i<num;i++)
    {
        cin>>a[i];
    }
    for(i=0;i<num;i++)
    {
        m=a[i];
        prime=prime_k(m);
        m=num-1;
        if(i==m)cout<<prime;
        else cout<<prime<<" ";
    }
}

Need increase array "unsigned long a[100]" to 15001