using System;
using System.Collections.Generic;
using System.Linq;
class Program {
    static void Main() {
        string ans = "impossible";
        Console.ReadLine();
        int[] ws = Console.ReadLine().Split().Select(int.Parse).ToArray();
        int sum = ws.Sum();
        if (sum % 2 == 0) {
            HashSet<int> leftW = new HashSet<int> { 0 };

            foreach (int w in ws) {
                leftW.UnionWith(leftW.Select(x => x + w).ToArray());
            }
            if (leftW.Contains(sum / 2)) ans = "possible";
        }
        Console.WriteLine(ans);
    }
}