Which of the following statement is correct about the program given below?

#include<iostream.h> 
enum xyz
{
    a, b, c
};
int main() 
{
    int x = a, y = b, z = c;
    int &p = x, &q = y, &r = z;
    p = ++x;
    q = ++y;
    r = ++c;
    cout<< p << q << r;
    return 0;
}

#include<iostream.h> 
int val = 0; 
class CuriousTab
{
    public: 
    CuriousTab()
    {
        cout<< ++val;
    }
    ~CuriousTab()
    {
        cout<< val--; 
    } 
}; 
int main()
{
    CuriousTab objCuriousTab1, objCuriousTab2, objCuriousTab3;
    {
        CuriousTab objCuriousTab4;
    } 
    return 0;
}

#include<iostream.h> 
class CuriousTab
{
    int Num; 
    public:
    CuriousTab(int x)
    {
        Num = x;
    }
    int CuriousTabFunction(void);
};
int CuriousTab::CuriousTabFunction(void)
{
    static int Sum = 0; 
    int Dec;
    Dec = Num % 10; 
    Num = Num / 10; 
    if((Num / 100)) CuriousTabFunction(); 
    Sum  = Sum * 10 + Dec; 
    return Sum;
}
int main()
{
    CuriousTab objCuriousTab(12345);
    cout<< objCuriousTab.CuriousTabFunction();
    return 0; 
}