using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text;

public class Program
{

    public void Proc()
    {
        int itemCount = int.Parse(Reader.ReadLine());
        this.Items = Reader.ReadLine().Split(' ').Select(a => int.Parse(a)).ToArray();

        int total = Items.Sum(a => a);
        if(total %2 !=0) {
            Console.WriteLine("impossible");
            return;
        }
        string ans = "impossible";
        if (getAns(0, total / 2)) {
            ans = "possible";
        }
        Console.WriteLine(ans);
    }

    private Dictionary<int, Dictionary<int, bool>> dic = new Dictionary<int, Dictionary<int, bool>>();
    private bool getAns(int idx, int remain) {
        if(idx >= this.Items.Length) {
            return remain == 0;
        }
        if(remain == 0) {
            return true;
        }
        if(remain < 0) {
            return false;
        }
        if(!dic.ContainsKey(idx)) {
            dic.Add(idx, new Dictionary<int, bool>());
        }
        if(dic[idx].ContainsKey(remain)) {
            return dic[idx][remain];
        }
        bool ret = getAns(idx + 1, remain - Items[idx]);
        if(!ret) {
            ret = getAns(idx + 1, remain);
        }
        dic[idx][remain] = ret;
        return ret;
    }

    private int[] Items;


    public class Reader
	{
		private static StringReader sr;
		public static bool IsDebug = false;
		public static string ReadLine()
		{
			if (IsDebug)
			{
				if (sr == null)
				{
					sr = new StringReader(InputText.Trim());
				}
				return sr.ReadLine();
			}
			else
			{
				return Console.ReadLine();
			}
		}
		private static string InputText = @"





3
1 2 3



";
	}

	public static void Main(string[] args)
	{
#if DEBUG
		Reader.IsDebug = true;
#endif
		Program prg = new Program();
		prg.Proc();
	}
}