using System;

namespace OmoriToTenbin3
{
    class Program
    {
        static int N;
        static int[] W;
        static int[] remainSum;
        static int totalHalf;

        static void Main(string[] args)
        {
            N = int.Parse(Console.ReadLine());
            W = new int[N];
            remainSum = new int[N];
            string[] vals = Console.ReadLine().Split(' ');
            int total = 0;
            for (int i = 0; i < N; i++)
            {
                W[i] = int.Parse(vals[i]);
                total += W[i];
            }

            if(total % 2 != 0)
            {
                Console.WriteLine("impossible");
                return;
            }

            totalHalf = total / 2;

            Array.Sort(W);
            Array.Reverse(W);
            remainSum[N-1] = W[N-1];
            for(int i=N-2; i >= 0; i--)
            {
                remainSum[i] = remainSum[i + 1] + W[i];
            }

            if(Search(0, 0))
            {
                Console.WriteLine("possible");
            }
            else
            {
                Console.WriteLine("impossible");
            }

        }

        static bool Search(int weight, int i)
        {


            if (weight == totalHalf)
            {
                return true;
            }
            else if(weight > totalHalf)
            {
                return false;
            }

            if (i >= N)
            {
                return false;
            }

            if(weight + remainSum[i] < totalHalf)
            {
                return false;
            }

            if(Search(weight+W[i], i+1))
            {
                return true;
            }
            if(Search(weight, i+1))
            {
                return true;
            }

            return false;

        }

    }
}