#include <iostream>
#include <cmath>


using namespace std;

int main() {

	double lenght, width, aWardrobe;
	cin >> lenght >> width >> aWardrobe;
	double dancers;

	double hallArea = (lenght*100) * (width*100);
	double wardrobeArea = aWardrobe*100 * aWardrobe*100;
	double benchArea = hallArea / 10;
	double dancerArea;
	dancerArea = 7040;
	double freeArea = hallArea - wardrobeArea - benchArea;

	dancers = freeArea / dancerArea;

	cout << floor(dancers);

	return 0;
}