using System;
using System.Linq;

class Program
{
    static void Main()
    {
        Console.ReadLine();
        int[] W = Console.ReadLine().Trim().Split(' ').Select(x => int.Parse(x)).ToArray();
        Array.Sort(W);
        int sum = 0;
        
        Array.ForEach(W,delegate(int i)
        {
            sum += i; 
        });

        bool flag = false;
        int harf = 0;

        foreach(int i in W){
            harf += i;
            if(sum / 2 == harf){
                flag = true;
                break;
            }
        }

        if(flag)
            Console.WriteLine("possible");
        else
            Console.WriteLine("impossible");

        }
}