using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;


class Magatro
{
    static int N = int.Parse(Console.ReadLine());
    const long MOD = 10000000000;
    static void Main()
    {
        long Integer = 0;
        long Fre = 0;
        for (int i = 0; i < N; i++)
        {
            string num = Console.ReadLine();

            bool pos = num[0] != '-';
            if (!pos)
            {
                num = num.Remove(0, 1);
            }
            string[] n = num.Split('.');
            if (pos)
            {
                Integer += long.Parse(n[0]);
                if (n.Length == 2)
                {
                    Fre += long.Parse(n[1].PadRight(10, '0'));
                }
            }
            else
            {
                Integer -= long.Parse(n[0]);
                if (n.Length == 2)
                {
                    Fre -= long.Parse(n[1].PadRight(10, '0'));
                }
            }
        }
        Integer += Fre / MOD;
        Fre %= MOD;
        bool Plus;
        if (Integer > 0)
        {
            Plus = true;
            if (Fre < 0)
            {
                Integer--;
                Fre += MOD;
            }
        }
        else if (Integer < 0)
        {
            Plus = false;
            if (Fre > 0)
            {
                Integer++;
                Fre -= MOD;
            }
            Fre *= -1;
            Integer *= -1;
        }
        else
        {
            Plus = Fre >= 0;
            if(!Plus)
            Fre *= -1;
        }
        if (!Plus)
        {
            Console.Write("-");
        }
        Console.Write("{0}.{1}", Integer, Fre.ToString().PadLeft(10, '0'));
        Console.WriteLine();
        
    }
}