using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        new Magatro().Solve();
    }
}

class Magatro
{
    private const double InfF=0.229415733870562;
    private int N;
    private int[]RPerf;
    private double F(int n)
    {
        double aa=1,bb=1;
        double bo=0,si=0;
        for(int i = 0;i<n;i++)
        {
            aa*=0.9;
            bb*=0.81;
            bo+=aa;
            si+=bb;
        }
        return Math.Sqrt(si)/bo;
    }
    private double f(int n)
    {
        return (F(n)-InfF)/(1-InfF)*1200;
    }
    private double g(int n)
    {
        return Math.Pow(2.0,(double)n/800);
    }
    private double minusg(double n)
    {
        return 800.0*Math.Log(n,2);
    }
            
            
    public void Solve()
    {    
        N=int.Parse(Console.ReadLine());
        RPerf=new int[N];
        for(int i=0;i<N;i++)
        {
            RPerf[i]=int.Parse(Console.ReadLine());
        }
        double aa=1;
        double bo=0;
        double si=0;
        for(int i=0;i<N;i++)
        {
            aa*=0.9;
            bo+=aa;
            si+=g(RPerf[i])*aa;
        }
        Console.WriteLine(Math.Round(minusg(si/bo)-f(N)));
        
    }
}