void insert_b4_search(int ai,int bj)// ai is the value we are looking for in the linklist . bi is the value od the new node
  {  node *temp;
   temp = head;
  while(temp != NULL && temp-> num != ai)//num=value
  {temp = temp -> nxt;
  if(temp == NULL){
    cout<<"ooo"<<endl;
   } }
  if (temp == head){
    insert_at_first(bj);//call add at first method
    }
   else if(temp == tail){
    insert_to_tail(bj);
    }
   else {  ptr = new node(bj,NULL,NULL);
    ptr->prev = new node(bj, ptr->prev, ptr);
     ptr->prev->prev->next = ptr->prev;
     }
    }