#include <iostream>


int main() {
	
	float position{};
	float relative_position;
	
	int speed;
	int length;
	int exten_speed;
	
	int ticks{};
	
	std::cin >> speed >> length >> exten_speed;
	
	while ( (relative_position = position/length) < 1 )
		{
			length+=exten_speed;
			position = relative_position * length;
			position+=speed;
			ticks++;
		}
	
	std::cout << ticks;
	
	return 0;
}