C lists, where am I wrong?

Question

I'm making a little program that should allow me to insert n numbers into an array. Subsequently these numbers must be inserted in a list, avoiding to insert duplicates. I think I'm close to the solution but I don't understand where I'm wrong. My idea is to insert the first element directly in the list without doing any checks, from the second element onwards, I scroll through the list of elements inserted and check if the number I am about to insert is already present, if yes I discard it otherwise I add a node to the list. Problem is, I've made some mistakes that I can't find. Can you help me?

    //This is the node
    struct node
    {
      int dato;         
      struct node *next; 
    };
    
int main()
{
 int i,j=0,n, control=0;
 int V[dmax];
  struct node *p, *prec, *head, *f;
  do
  {
  printf("type dim of array\n");
  scanf("%d",&n); 
  }
  while(n<1 || n>dmax);
  loadArray(V,n); 

 //______________________
  for(i=0; i<n; i++){
    control = 0, j=0;
    if(i==0){
        p=malloc(sizeof(struct node));
            head = p;
    p->dato=V[i];
    }else{
      while(j<i){
        f=head;
      if(V[i]==f->dato){
        control = 1;
        j++;
       //maybe break;?
      }else{
          f = f->next;
          j++;
        }
      }//while                         
    }//else
    if ( control == 1)
      printf("%d discarded\n", i);
    else{
      p=malloc(sizeof(struct node));
      p->dato=V[i];
      prec->next = p;
      prec = p;
    }
    p->next=NULL;

  }//for
  p=head;
    printf("print list\n");
    while(p != NULL){

    printf("%d\n",p->dato);
    p = p->next;
    }

}