DanceHall

import java.util.Scanner;

public class DancingHall {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        double L = Double.parseDouble(scan.nextLine());
        double W = Double.parseDouble(scan.nextLine());
      double A = Double.parseDouble(scan.nextLine());
        double zala = L * 100 * W * 100;
        double garderob = A * 100 * A * 100;
        double pejka = zala / 10;
        double freeSpace = zala - garderob - pejka;
        double tanciori = freeSpace / (40 + 7000);
        System.out.println((int)Math.floor(tanciori));

    }
}