Dance Hall

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        double l = Double.parseDouble(scanner.nextLine()),
                w = Double.parseDouble(scanner.nextLine()),
                a = Double.parseDouble(scanner.nextLine()),
                space = l * w - (l * w / 10) - a * a;

        int dancers = (int) (space / 0.7040);

        System.out.println(dancers);
    }
}