Reference to 'begin' is ambiguous

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
struct Stack {
        int info;
        Stack * next;
} *begin, *t;
//------------ Äåêëàðàöèè ïðîòîòèïîâ ôóíêöèé ïîëüçîâàòåëÿ ----------
Stack* InStack(Stack*, int);
Stack* OutStack(Stack*, int);
void View(Stack*);
void Del_All(Stack **);
 
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
int i, in, n = StrToInt(Edit1->Text);
        if(begin != NULL){
                ShowMessage("Îñâîáîäèòå ïàìÿòü!");
                return;
        }
        for(i = 1; i <= n; i++){
                in = random(201)-100;
                begin = InStack(begin, in);
        }
        Memo1->Lines->Add("Ñîçäàëè " + IntToStr(n) + " -òü.");
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
        int i, in, n = StrToInt(Edit1->Text);
        for(i = 1; i <= n; i++){
                in = random(201)-100;
                begin = InStack(begin, in);
        }
        Memo1->Lines->Add("Äîáàâèëè " + IntToStr(n) + " -òü.");
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button3Click(TObject *Sender)
{
        if(!begin){
                ShowMessage("Ñòåê Ïóñò!");
                return;
        }
        Memo1->Lines->Add("--- Ýëåìåíòû ---");
        View(begin);
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button4Click(TObject *Sender)
{
if (begin != NULL) Del_All(&begin);
        ShowMessage("Ïàìÿòü îñâîáîæäåíà!");
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button5Click(TObject *Sender)
{
if(begin != NULL) Del_All(&begin);
        Close();
 
}
//---------------------------------------------------------------------------
Stack* InStack(Stack *p, int in) {
        Stack *t = new Stack;
        t -> info = in;
        t -> next = p;
        return t;
}
//---------------------------------------------------------------------------
Stack* OutStack(Stack* p, int *out)   {
Stack *t = p;
*out = p -> info;
p = p -> next;
delete t;
return p;
}
 
//----------------- Ôóíêöèÿ ïðîñìîòðà Ñòåêà----------------------------------
void View(Stack *p) {
        Stack *t = p;
        while( t != NULL) {
                Form1->Memo1->Lines->Add("   " + IntToStr( t->info));
                t = t -> next;
        }
}
//----------------------- Ôóíêöèÿ îñâîáîæäåíèÿ ïàìÿòè -----------------------
void Del_All(Stack **p) {
        while(*p != NULL) {
                t = *p;
                *p = (*p) -> next;
                delete t;
        }
}
//----------------- Ôóíêöèÿ ñîðòèðîâêè Ñòåêà ÏÅÐÂÛÉ ÑÏÎÑÎÁ--------------------
void Sort_p(Stack **p) {
    Stack *t = NULL, *t1, *r;
    if ((*p) -> next -> next == NULL) return;
    do {
            for (t1=*p; t1-> next->next  != t; t1=t1-> next)
                if (t1->next->info  >  t1-> next-> next-> info){
                            r = t1->next->next;
                            t1 -> next -> next = r -> next;
                            r-> next =t1-> next;
                            t1-> next = r;
                }
            t= t1-> next;
    } while ((*p)-> next -> next != t);
}
//----------------- Ôóíêöèÿ ñîðòèðîâêè Ñòåêà ÂÒÎÐÎÉ ÑÏÎÑÎÁ--------------------
void Sort_info(Stack *p) {
    Stack *t = NULL, *t1;
    int r;
    do {
            for (t1=p; t1 -> next != t; t1 = t1-> next)
                if (t1-> info > t1-> next -> info)  {
                                r = t1-> info;
                                t1-> info = t1-> next -> info;
                                t1-> next -> info = r;
                    }
            t = t1;
    } while (p -> next != t);
}
//------------------------ Ñîðòèðîâêà ÏÅÐÂÛÉ ÑÏÎÑÎÁ--------------------------
void __fastcall TForm1::Button6Click(TObject *Sender)
{
int k=999;
begin = InStack(begin, k);
Sort_p(&begin);
begin = OutStack(begin, &k);
 
}
//------------------------ Ñîðòèðîâêà Âòîðîé ÑÏÎÑÎÁ--------------------------
 
void __fastcall TForm1::Button7Click(TObject *Sender)
{
Sort_info(begin);
}
//---------------------------------------------------------------------------