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

class Magatro
{
    static void Main()
    {
        long[] q = Console.ReadLine().Split(' ').Select(s => long.Parse(s)).ToArray();
        long coin = q[0] / 5;
        Console.WriteLine((double)coin * q[1] / q[2]);
    }

}