package com.company;

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());
double W = Double.parseDouble(scanner.nextLine());
double A = Double.parseDouble(scanner.nextLine());

int totalZala = (int)((L * 100) * (W * 100));
int totalGarderob = (int)((A * 100) * (A * 100));
int totalPeika = totalZala / 10;
int freeSpace = totalZala - totalGarderob - totalPeika;
int numberOfDancers = freeSpace / (40 + 7000);
        System.out.printf("%.0f",Math.floor(numberOfDancers));

    }
}