using System;
using System.Collections.Generic;
using System.Linq;

namespace yukicoder
{
    public class Program
    {
        public static void Main()
        {
            var n = int.Parse(Console.ReadLine());
            var w = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var k = w.Sum();
            var c = true;
            if (k % 2 != 0)
            {
                Console.WriteLine("impossible");
            }
            else
            {
                var sum = new List<int>[n];
                sum[0] = new List<int> { 0, w[0] };
                for (var i = 1; i < n; i++)
                {
                    sum[i] = sum[i - 1].Select(x => x + w[i]).Where(x => x <= k / 2).ToList();
                    if (sum[i].Any(x => x == k / 2))
                    {
                        Console.WriteLine("possible");
                        c = false;
                        break;
                    }
                }
                if (c)
                {
                    Console.WriteLine("impossible");
                }
            }
        }
    }
}