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

namespace Test01
{
    class Program
    {
        
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            string[] input = Console.ReadLine().Split(' ');

            int[] w = new int[N + 1];
            for(int i = 1; i <= N; i++)
            {
                w[i] = int.Parse(input[i - 1]);
            }

            int sum = w.Sum();
            if(sum % 2 == 1)
            {
                Console.WriteLine("impossible");
                return;
            }

            int max = sum / 2;
            bool[] dp = new bool[max + 1];

            dp[0] = true;
            w = w.OrderBy(x => x).ToArray();
            for(int i = 1; i <= N; i++)
            {
                for(int j = max; j >= 0; j--)
                {
                    if (w[i] + j <= max) dp[w[i] + j] |= dp[j];
                }
            }

            if (dp[max]) Console.WriteLine("possible");
            else Console.WriteLine("impossible");
        }
    }
}