#include <iostream>

class foo
{
public:
    int val;
    
    foo (int i) : val(i) {}
    
    bool operator < (const foo &other);
};

 bool foo::operator < (const foo &other)
 {
     return val < other.val;
 }

int main()
{
    foo f(5), g(4);
    std::cout << std::boolalpha << (f < g) << '-' << (g < f);
}