using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        long[] su = Console.ReadLine().Split().Select(long.Parse).ToArray();

        long coin5 = su[0] / 5;

        Console.WriteLine((double)coin5 * su[1] / su[2]);
        Console.Read();
    }
}