Search in a doubly linked list

An array of instances of the contact structure is read from the file. These instances form a doubly linked list. The search() function outputs the entire list starting with the sequence number that the user enters. To save time with large lists, I made a search for an element from 2 sides( depending on the position of the element relative to the center of the list) when entering the list from the head-it works, but when entering from the end, an error pops up, because the last one in the list is the first one the element. How can I fix this error?

#include "stdafx.h"
#include<cstdlib>
#include<string.h>
#include<iostream>

struct contact
{
    char nomer[50];
    char adress[50];
    char sname[50];
};

struct Node
{
    char nomer[50];
    char adress[50];
    char sname[50];
    Node *next, *prev;
};typedef Node *PNode;

PNode CreateNode(contact buf)
{
    PNode NewNode = new Node;
    strcpy(NewNode->nomer, buf.nomer);
    strcpy(NewNode->adress, buf.adress);
    strcpy(NewNode->sname, buf.sname);
    NewNode->next = NULL;
    NewNode->prev = NULL;
    return NewNode;
}

void AddNode(PNode &Head, PNode &Tail, PNode NewNode)
{
    NewNode->next = NULL;
    NewNode->prev = Tail;
    if (Tail) Tail->next = NewNode;
    Tail = NewNode;
    if (!Head) Head = Tail;
}

void AddAfter(PNode &Head, PNode &Tail, PNode p, PNode NewNode)
{   
    if (p==Tail)
{
    NewNode->prev = Tail;
    Tail = NewNode;
}
    NewNode->next = p->next;
    NewNode->prev = p;
    if (p->next)
    p->next->prev = NewNode;
    p->next = NewNode;
    Tail= NewNode;// add
}
void AddBefore(PNode &Head, PNode &Tail, PNode p, PNode NewNode)
{
    if (Head == p)
    {
        NewNode->next = Head;
        Head = NewNode;
    }
    else
    {
        NewNode->prev = p->prev;
        NewNode->next = p;
        p->prev->next = NewNode;
        p->prev = NewNode;
    }
}    


void ShowTwoLinkedList(PNode Head)
{
    PNode p = Head;
    while (p != NULL)
    {
        printf("%s\n", p->sname);
        p = p->next;
    }
    fflush(stdin);
    getchar();
}    

void AddAndSort(contact buf, PNode Head, PNode Tail)
{
    PNode NewNode = CreateNode(buf);
    PNode p = Head;
    while (p->next && (strcmp(p->sname, NewNode->sname) < 0))
        p = p->next;
    if ((strcmp(p->sname, NewNode->sname) < 0))
        AddAfter(Head, Tail, p, NewNode);
    else
        AddBefore(Head, Tail, p, NewNode);
}
int Search(PNode Head,PNode Tail,int NumOfPosition, int kol_el)
{
    if ((NumOfPosition < 1) || (NumOfPosition > (kol_el)))
    {
        printf("Ошибка:некорректный ввод позиции в списке.\n");
        return -1;
    }
    else if (kol_el / 2 >= NumOfPosition)
        {//cлева
            int count = 1;
            PNode p = Head;
            while (count != NumOfPosition)
            {
                p = p->next;
                count++;
            }
            system("cls");
            printf("Информация по запросу:\n");
            while (p->next)
            {
                printf("%s\n", p->sname);
                printf("%s\n", p->adress);
                printf("%s\n", p->nomer);
                printf("\n\n");
                p = p->next;
            }
            system("pause");
        }
        else 
        {
            //справа
            int count = kol_el;
            PNode p = Tail;
            while (count != NumOfPosition)
            {
                p = p->prev;
                count--;
            }
            system("cls");
            printf("Информация по запросу:\n");
            while (p->next)
            {
                printf("Информация по запросу:\n");
                printf("%s\n", p->sname);
                printf("%s\n", p->adress);
                printf("%s\n", p->nomer);
                printf("\n\n");
                p = p->next;
            }
            system("pause");

        }
}    

int main()
{
    setlocale(LC_ALL, "RUS");
    int rezh;
    PNode Head = NULL;
    PNode Tail = NULL;
    FILE *f;
    f = fopen("telbook.dat", "r+b");
    fseek(f, 0, SEEK_END);
    int size = ftell(f);
    int kol_el = size / sizeof(contact);
    contact *buf = new contact[kol_el];
    fseek(f, 0, SEEK_SET);
    fread(buf, sizeof(contact), kol_el, f);
    fclose(f);
        do {
        system("cls");
        const int NotUsed = system("color 03");
        printf("Выберите действие:\n");
        printf("1.Показать список.\n");
        printf("2.Создание+сортировка.\n");
        printf("3.Поиск по списку.\n");
        printf("4.Выйти из программы.\n");
        scanf_s("%d", &rezh);
        switch (rezh)
        {
        case 1:
        {
            ShowTwoLinkedList(Head);
            break;
            }    

        case 2:
        {
            PNode NewNode = CreateNode(buf[0]);
            AddNode(Head, Tail, NewNode);
            for (int i = 1; i < kol_el; i++)
                AddAndSort(buf[i], Head, Tail);
            break;
        }

        case 3:
        {
            system("cls");
            printf("Введите номер:\n");
            int NumOfPosition;
            scanf("%d", &NumOfPosition);
            Search(Head,Tail,NumOfPosition,kol_el);
        }
        }
    } while (rezh != 4);
    system("pause");
    return 0;