using System; using System.Linq; using System.Collections.Generic; namespace yukicoder { class pg { static void Main(string[] args) { int N = int.Parse(Console.ReadLine()); var weights = Console.ReadLine().Split(' ').Select(c => int.Parse(c)).OrderBy(c => c).ToList(); int total = weights.Sum(); if(total % 2 == 1) { Console.WriteLine("impossible"); return; } int harfTotal = total / 2; var explorer = new bool[harfTotal + 1]; var oldExplorer = new bool[harfTotal + 1]; for(int i = 0;i < weights.Count;i++) { if(weights[i] > harfTotal)continue;//配列の範囲外の時 for(int q = 1;q < harfTotal + 1;q++) { int pair = q + weights[i]; if(!oldExplorer[q] || pair > harfTotal)continue; explorer[pair] = true; } explorer[weights[i]] = true; Array.Copy(explorer,oldExplorer,explorer.Length); } if(explorer[harfTotal]) { Console.WriteLine("possible"); }else { Console.WriteLine("impossible"); } for(int i = 0;i < explorer.Length;i++) { Console.WriteLine(i + " " + explorer[i]); } } } }