Custom Overload New and Delete Operator

// Global new and delete operator
void * operator new(size_t size)
{
   cout<< "Overloading new operator with size: " << size << endl;
   void * p = malloc(size); 
   return p;
}
void operator delete(void * p)
{
   cout<< "Overloading delete operator " << endl;
   free(p);
}

class Details
{
    int marks;
    int rollno;
public:
    Details( int marks, int rollno) : marks(marks), rollno(rollno) 
    { 
         cout << "Details Constructor called" << endl;
    }
    void display()
    {
        cout<< "Marks:" << marks << endl;
        cout<< "rollno:" << rollno << endl;
    }
    ~Details() {  cout << "Details Destructor called" << endl;}
};
class student
{
    string name;
    int age;
    Details* d;
public:
    student()
    {
        cout<< "Constructor is called\n" ;
    }
    student(string name, int age, int marks, int rollno) : name{name},age{age} 
    {
        cout << " Student Constructor called" << endl;
        d = new Details{marks, rollno};
    }
    void display()
    {
        cout<< "Name:" << name << endl;
        cout<< "Age:" << age << endl;
        d->display();
    }
    ~student() { cout << " Student Destructor called" << endl; delete d;}   
};
// Driver function
int main()
{
    student * p = new student("Yash", 24 , 5, 1); 
    p->display();
    delete p;
}

Output:

Overloading new operator with size: 29
Overloading new operator with size: 24
Student Constructor called
Overloading new operator with size: 8
Details Constructor called
Name:Yash
Age:24
Marks:5
rollno:1
Student Destructor called
Details Destructor called
Overloading delete operator 
Overloading delete operator 
Overloading delete operator

I expected new and delete opeator functions to be called 2 times (for student and details). But output of the Program shows new and delete operator functions gets called 3 times. Why ?