using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static string[] SList(long n) => Enumerable.Repeat(0, (int)n).Select(_ => ReadLine()).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        CreateLf();
        var n = NN;
        var p = new int[n];
        for (var i = 0; i < n; ++i) p[i] = NN;
        var ch = 0.0;
        var pa = 0.0;
        var mul = 0.9;
        for (var i = 0; i < n; ++i)
        {
            ch += Gx(p[i]) * mul;
            pa += mul;
            mul *= 0.9;
        }
        WriteLine(Math.Floor(0.5 + RevGx(ch / pa) - Sf(n)));
    }
    static double Sf(int n)
    {
        return 1200 * (lf[n] - lf[^1]) / (lf[1] - lf[^1]);
    }
    static double Gx(int x)
    {
        return Math.Pow(2, x / 800.0);
    }
    static double RevGx(double y)
    {
        return 800 * Math.Log2(y);
    }
    static double[] lf;
    static void CreateLf()
    {
        var mul = 0.9;
        var ch = 0.0;
        var pa = 0.0;
        var len = 1000;
        lf = new double[len];
        for (var i = 1; i < len; ++i)
        {
            ch += mul * mul;
            pa += mul;
            mul *= 0.9;
            lf[i] = Math.Sqrt(ch) / pa;
        }
    }
}