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

class Magatro
{

    static void Main()
    {
        int N = int.Parse(Console.ReadLine());
        int[] w = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
        if (w.Sum() % 2 == 1)
        {
            Console.WriteLine("impossible");
            return;
        }
        int sum = w.Sum();
        int ans = w.Sum() / 2;
        bool[] dp = new bool[sum+1];
        dp[0] = true;
        for(int i = 0; i < N; i++)
        {
            for(int j = sum - w[i]; j >= 0; j--)
            {
                dp[j + w[i]] |= dp[j];

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

 
}