using System;
using System.Linq;

namespace _379
{
    class Program
    {
        static void Main(string[] args)
        {
            long[] x = Console.ReadLine().Split().Select(long.Parse).ToArray();
            x[0] /= 5;
            long a = x[0] * x[1];
            long b = x[2];
            double ret = a;
            ret /= b;
            Console.WriteLine(ret);
        }
    }
}