#include <iostream>

struct Class {
  int i;
  Class(int i_) : i(i_)  {}
};

Class operator+(const Class& c1, const Class& c2) {
  return Class(c1.i + c2.i);
}

int main() {
  Class c1(10), c2(20);
  Class c3 = c1 + c2;
  std::cout << c3.i << "\n";
}