using System;
using System.Linq;

namespace _0379
{
    class Program
    {
        static void Main(string[] args)
        {
            var s = Console.ReadLine().Split().Select(n => long.Parse(n)).ToArray();
            var c = s[0] / 5;
            var g = s[1] * c * 1.0;

            Console.WriteLine(g / s[2]);
        }
    }
}