#include <iostream>

class Logger {
public:
	virtual void log(double step, double sq) {
	}
};

class NoLogger : public Logger {
};

class StdOutLogger : public Logger {
public:
	virtual void log(double step, double sq) {
		std::cout << "Step: " << step
			<< ", Square: " << sq << std::endl;
	}
};


double f(double x) {
	return x*x*x -3*x*x + 5;
}


double square(Logger * log, double step) {
	double s = 0;
	for ( double x = 0; x < 10; x += step )
		s += f(x) * step;
	log->log(step, s);
	return s;
}

double square(Logger * log) {
	double step = 2;
	double s1, s2 = square(log, step);
	do {
		s1 = s2;
		step /= 2;
		s2 = square(log, step);
	} while (abs(s1-s2) > 0.00001);

	return s2;
}

void main() {
	std::cout << square(new StdOutLogger());
}