using System;
using System.Text;
using System.Collections.Generic;

public class Program
{
    public void Proc() {
        Reader.IsDebug = false;
        int omoriCount = int.Parse(Reader.ReadLine());
        
        this.OmoList.AddRange(Reader.GetInt());
        int total = 0;
        foreach (int num in this.OmoList)
        {
            total += num;
        }
        this.OmoList.Sort();
        this.OmoList.Reverse();
        bool ans = (total % 2 == 0);
        if(ans) {
            ans = CanBalance(0, total / 2);
        }
        Console.WriteLine(ans?"possible":"impossible");
    }
    
    private List<int> OmoList = new List<int>();
    
    Dictionary<int,Dictionary<int, bool>> dic = new Dictionary<int,Dictionary<int, bool>>();
    private bool CanBalance(int idx, int remain) {
        if(!dic.ContainsKey(idx)) {
            dic.Add(idx, new Dictionary<int, bool>());
        }
        if(dic[idx].ContainsKey(remain)) {
            return dic[idx][remain];
        }
        if(remain == 0) {
            return true;
        }
        if(remain < 0) {
            return false;
        }
        if (idx >= this.OmoList.Count) {
            return false;
        }
        bool ans = false;
        for (int i=idx; i<this.OmoList.Count; i++) {
            if(this.OmoList[i] <= remain) {
                ans = ans || this.CanBalance(i + 1, remain - this.OmoList[i]);
                if(ans) {
                    break;
                }
            }
        }
        dic[idx].Add(remain, ans);
        return ans;
    }

    public class Reader {
        private static String InitText = @"




7
20 47 73 69 26 62 89




        ";
        
        private static System.IO.StringReader sr = null;
        
        public static bool IsDebug = true;
        
        public static string ReadLine() {
            if(IsDebug) {
                if(sr == null) {
                    sr = new System.IO.StringReader(InitText.Trim());
                }
                return sr.ReadLine();
            } else {
                return Console.ReadLine();
            }
        }
        public static int[] GetInt(char delimiter = ' ') {
            string[] inpt = ReadLine().Split(delimiter);
            int[] ret = new int[inpt.Length];
            for(int i=0; i<inpt.Length; i++) {
                ret[i] = int.Parse(inpt[i]);
            }
            return ret;
        }
    }
    public static void Main(string[] args)
    {
        Program prg = new Program();
        prg.Proc();
    }
}