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

namespace _01.Task
{
    class Program
    {
        static void Main(string[] args)
        {
            long n = long.Parse(Console.ReadLine());
            long s = long.Parse(Console.ReadLine());
            decimal p = decimal.Parse(Console.ReadLine());
            decimal oneRealm = 500;

            decimal sheets = n * s;
            decimal neededReams = sheets / oneRealm;

            Console.WriteLine("{0:F2}", neededReams * p);
        }
    }
}