﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _1___Problem
{
    class Program
    {
        static void Main(string[] args)
        {
            int studentsCount = int.Parse(Console.ReadLine());
            int sheetPerStudent = int.Parse(Console.ReadLine());
            decimal priceForPack = decimal.Parse(Console.ReadLine());

            int totalCountSheets = studentsCount * sheetPerStudent;

            decimal totalPacksOfSheets = (decimal)totalCountSheets / 500;

            Console.WriteLine("{0:F2}", (decimal)totalPacksOfSheets * priceForPack);
        }
    }
}
