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

class Program
{
    static string InputPattern = "Input4";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("3");
            WillReturn.Add("1 2 3");
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("5");
            WillReturn.Add("1 2 3 4 5");
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("15");
            WillReturn.Add("62 8 90 2 24 62 38 64 76 60 30 76 80 74 72");
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    struct JyoutaiDef
    {
        internal int CurrP;
        internal HashSet<int> SelectedOmoriIndSet;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();

        int[] OmoriArr =
            InputList.Skip(1).SelectMany(X => X.Split(' '), (X, Y) => int.Parse(Y)).ToArray();

        //事前に総和の半分を求めておく
        int OmoriSum = OmoriArr.Sum();

        //総和が奇数ならその時点で解なしとなる
        if (OmoriSum % 2 == 1) {
            Console.WriteLine("impossible");
            return;
        }

        var stk = new Stack<JyoutaiDef>();
        JyoutaiDef WillPush;
        WillPush.CurrP = 0;
        WillPush.SelectedOmoriIndSet = new HashSet<int>() { 0 }; //1つめの重りは必ず選択するとする
        stk.Push(WillPush);

        while (stk.Count > 0) {
            JyoutaiDef Popped = stk.Pop();

            //クリア判定
            int LeftOmoriSum = DeriveOmoriSum(OmoriArr, Popped.SelectedOmoriIndSet);

            if (LeftOmoriSum == OmoriSum / 2) {
                Console.WriteLine("解を発見しました");
                Console.WriteLine("選択する重りは");
                foreach (int EachInd in Popped.SelectedOmoriIndSet) {
                    Console.WriteLine(OmoriArr[EachInd]);
                }
                Console.WriteLine("選択しない重りは");
                for (int I = 0; I <= OmoriArr.GetUpperBound(0); I++) {
                    if (Popped.SelectedOmoriIndSet.Contains(I)) continue;
                    Console.WriteLine(OmoriArr[I]);
                }
                Console.WriteLine("possible");
                return;
            }
            else if (LeftOmoriSum > OmoriSum / 2) {
                continue; //総和の半分を超えたら枝切り
            }

            if (Popped.CurrP > OmoriArr.GetUpperBound(0)) continue;

            //重りを選択する経路のPush
            WillPush.CurrP = Popped.CurrP + 1;
            WillPush.SelectedOmoriIndSet = new HashSet<int>(Popped.SelectedOmoriIndSet) { WillPush.CurrP };
            stk.Push(WillPush);

            //重りを選択しない経路のPush
            WillPush.SelectedOmoriIndSet = Popped.SelectedOmoriIndSet;
            stk.Push(WillPush);
        }
        Console.WriteLine("impossible");
    }

    //重りの添字Listを引数として、重りの合計を求める
    static int DeriveOmoriSum(int[] pOmoriArr, HashSet<int> pSelectedOmoriIndSet)
    {
        int WillReturn = 0;
        for (int I = 0; I <= pOmoriArr.GetUpperBound(0); I++) {
            if (pSelectedOmoriIndSet.Contains(I)) {
                WillReturn += pOmoriArr[I];
            }
        }
        return WillReturn;
    }
}