how to pass the value '4' in the parameter 'y' insyead of x in the third constructor call? If it is possible then please tell the answer. 

```
#include<iostream>

class Test // class created
{   
    int a,b,sum; 
    public:
    Test(int x=0,int y=0) // constructor created
    {
        a=x;
        b=y;
        sum= a+b;
        cout<<"X="<<x<<"\t"<<"Y="<<y<<"\t"<<"Sum ="<<sum<<"\n";
    }
};

void main()
{
    Test t1; // constructor calling without any values
    Test t2(2,4); // same as above but with two values
    Test t3(4); // it is only with a single value
    getch();
}

```

> 
> how to pass '4' in 'y' instead of 'x' in 3rd object creation?
> 
> 
>