﻿using System;

class Program
{
    static void Main()
    {
        int students = int.Parse(Console.ReadLine());
        int sheetsPaper = int.Parse(Console.ReadLine());
        double price = double.Parse(Console.ReadLine());

        double needPaper = students * sheetsPaper; 
        double reams = needPaper / 500;
        double needPrice = reams * price;

        Console.WriteLine("{0:f2}",needPrice);
    }
}