using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace foryuki
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());
            var w = ConvertStringArrayToIntArray(Console.ReadLine().Split());
            if (w.Sum() % 2 == 1)
            {
                Console.WriteLine("impossible");
                return;
            }
            int k = w.Sum();

            var d = new bool[k + 1];
            d[0] = true;
            for (int i = 1; i < d.Length; i++)
            {
                d[i] = false;
            }

            for (int i = 0; i < w.Length; i++)
            {
                for (int j = k; j >= 0; j--)
                {
                    if (d[j] == true)
                    {
                        d[j + w[i]] = true;
                    }
                }
            }

            if (d[k / 2])
            {
                Console.WriteLine("possible");
            }
            else
            {
                Console.WriteLine("impossible");
            }

        }

        //-------------------------------------------------------------

        static int[] ConvertStringArrayToIntArray(string[] array)
        {
            return Array.ConvertAll(array, str => int.Parse(str));
        }

        static List<int> ConvertStringArrayToIntList(string[] str)
        {
            var list = new List<int>();
            foreach (var c in str) list.Add(int.Parse(c));
            return list;
        }
    }
}