Dance Hall

import java.util.Scanner;

public class DanceHall {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double L = Double.parseDouble(scanner.nextLine());
        double W = Double.parseDouble(scanner.nextLine());
        double A = Double.parseDouble(scanner.nextLine());


        double room = (L * 100) * (W * 100);
        double wardrobe = (A * 100) * (A * 100);
        double bench = room/10;
        double freeSpace = room-wardrobe-bench;
        double people = freeSpace / (40 + 7000);

        System.out.printf("%.0f",Math.floor(people));




    }
}