using System;
using System.Linq;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        var a = new long[n];
        var b = new long[n];
        for (int i = 0; i < n; i++)
        {
            var s = Console.ReadLine().Split('.');
            a[i] = long.Parse(s[0]);
            if (s.Length > 1)
                b[i] = long.Parse(s[1].PadRight(10, '0'));
            if (s[0][0]=='-')
                b[i] = -b[i];
        }

        long t = 10000000000;

        long asum = a.Sum();
        long bsum = b.Sum();
        asum += bsum / t;
        if (bsum < 0)
            bsum -= bsum;
        bsum -= bsum / t * t;

        Console.WriteLine("{0}.{1}", asum, bsum.ToString("D10"));
    }
}