#include
class Fuel;
class Engine
{
int a,b;
public:
Engine(int xa=1,int xb=2){a=xa;b=xb;};
friend class Fuel;
int &geta(){return a;}
int &getb(){return b;}
};
class Fuel
{
Engine e;
public:
void show();
};
void Fuel::show()
{cout