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

#include<iostream.h> 
int i, j; 
class AptitudeCrack
{
    public:
    AptitudeCrack(int x = 0, int y = 0)
    {
        i = x; 
        j = x; 
        Display();
    }
    void Display()
    {
        cout<< j <<" ";
    } 
}; 
int main()
{
    AptitudeCrack objAptitude(10, 20); 
    int &s = i; 
    int &z = j; 
    i++;
    cout<< s-- << " " << ++z; 
    return 0; 
}