DanceHall

import java.util.Scanner;

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

        double lengthL = Double.parseDouble(scanner.nextLine());
        double wigthW = Double.parseDouble(scanner.nextLine());
        double gardA = Double.parseDouble(scanner.nextLine());

        double areaHall = (lengthL * 100) * (wigthW * 100);
        double areaGar = (Math.pow(gardA, 2)) * 100;
        double peika = areaHall / 10;
        double freeSpace = areaHall - areaGar - peika;
        double dancers = freeSpace / (40 + 7000);

        System.out.println( Math.floor(dancers));
    }
}