using System;

class ComputerFirm
{
    static void Main()
    {
        double allSales = 0;
        double allRate = 0;

        int n = int.Parse(Console.ReadLine());
        for (int i = n; i > 0; i--)
        {
            int input = int.Parse(Console.ReadLine());
            int rate = input % 10;
            int sales = input / 10;

            switch (rate)
            {
                case 3: allSales += 0.5 * sales; break;
                case 4: allSales += 0.7 * sales; break;
                case 5: allSales += 0.85 * sales; break;
                case 6: allSales += 1.00 * sales; break;
            }
            allRate += rate;

        }
        Console.WriteLine($"{allSales:f2}/n{allRate / n:f2}");
    }
}