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

class P
{
    static int[] w;
    static bool dfs(int i, int sum, int goal)
    {
        bool ret = false;
        if (goal == sum)
        {
            ret = true;
        }
        else if (goal <sum || i == 0)
        {
            ret = false;
        }
        else
        {
            ret = dfs(i - 1, sum + w[i], goal) || dfs(i - 1, sum, goal);
        }
        return ret;
    }
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        string[] _ = new string[n];
        _ = Console.ReadLine().Split(' ');
        n = _.Length;
        w = new int[n];
        int sum = 0;
        string ans = "";
        for (int i = 0; i < _.Length; i++)
        {
            w[i] = int.Parse(_[i]);
            sum += w[i];
        }

        if (sum % 2 == 0)
        {
            sum /= 2;
            Array.Sort(w);
            if (sum > w.Last())
            {
                ans = dfs(n - 1, 0, sum) ? "possible" : "impossible";
            }
            else
            {
                ans = "impossible";
            }
        }
        else
        {
            ans = "impossible";
        }

        Console.WriteLine(ans);
    }
}