using System; using System.Linq; namespace OmoriTenbin { class Program { static void Main(string[] args) { int N = int.Parse(Console.ReadLine()); int[] P = Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray(); string R = MainProcess(N, P); Console.WriteLine(R); } private static string MainProcess(int N, int[] P) { const string imp = "impossible"; const string pos = "possible"; int sum = 0; foreach(int p in P) sum += p; if (sum % 2 != 0) return imp; int hlf = sum / 2; int max = P.Max(); if (max > hlf) return imp; if (max == hlf) return pos; bool[] W = new bool[sum + 1]; for (int i = 0;i < N ; i++) { W[P[i]] = true; for (int j = sum - 1 - P[i]; j > 0; j--) { W[j+ P[i]] |= W[j]; if (W[j + P[i]] && j + P[i] == hlf) return pos; } } return imp; } } }