lst-0040-godb.cpp
//#(execute) c++; compiler:g132; options:-O3 -std=c++23; libs:-
// https://godbolt.org/z/Pr76Y55P4
class Rect {
int area_; // private data
public:
int x_, y_;
void set(int x, int y) { x_=x; y_=y; area_=x_*y_; }
int calc() { return area_; }
};