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

class A
{
	static void Main()
	{
		long[] xs = Console.ReadLine().Split(' ').Select(x => long.Parse(x)).ToArray();

		Console.WriteLine(string.Format("{0:f13}\n", ((1.0 *((xs[0] / 5) * xs[1])) / xs[2])));
	}
}