#include <iostream>
class Foo {
public:
Foo(int argX) : Foo(argX, defaultYValue) {}
Foo(int argX, int argY) : x(argX), y(argY) {};
public:
const int x;
const int y;
const int defaultYValue = -1;
};
int main() {
Foo foo(42);
std::cout << "Y value is: " << foo.y << std::endl;
return 0;
}