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

namespace omori
{
    class Program
    {
        static void Main(string[] args)
        {
            var str0 = int.Parse(Console.ReadLine());
            var str1 = Console.ReadLine().Split(' ');

            //答えの出現判定
            var hantei = new bool[100 * 100];
            for (int i = 0; i < hantei.Length; i++)
            {
                hantei[i] = false;
            }

            long total = 0;
            foreach (var item in str1)
            {
                total += int.Parse(item);
                hantei[total] =true;
            }

            if (((total % 2) == 0) & (hantei[total/2] == true))
            {
                Console.WriteLine("possible");
            }
            else
            {
                Console.WriteLine("impossible");
            }
        }
    }
}