using System;
using System.Linq;

namespace _19._10._31._4
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            var a = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            Array.Sort(a);

            if (a.Sum() % 2 == 0 && n > 1)
            {
                int sum1 = a[n - 1]; int sum2 = a[n - 2];
                for (int i = n - 3; i >= 0; i--)
                {
                    if (sum1 < sum2)
                        sum1 += a[i];
                    else
                        sum2 += a[i];
                }
                if(sum1 == sum2)
                    Console.WriteLine("possible");return;
            }
            Console.WriteLine("impossible");
        }
    }
}