using System;

namespace Zala
{
    class Program
    {
        static void Main(string[] args)
        {
            double L = double.Parse(Console.ReadLine());
            double W = double.Parse(Console.ReadLine());
            double A = double.Parse(Console.ReadLine());

            double zala = L * 100 * W * 100;
            double garderob = A * 100 * A * 100;
            double pejka = zala / 10;
            double tanci = zala - garderob - pejka;
            double tanciori = tanci / (40 + 7000);

            Console.WriteLine(Math.Floor(tanciori));
        }
    }
}