import java.io.*; import java.util.*; import java.util.stream.*; public class Main { static int[] weights; static boolean[][] dp; public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); int n = sc.nextInt(); weights = new int[n]; int total = 0; for (int i = 0; i < n; i++) { weights[i] = sc.nextInt(); total += weights[i]; } if (total % 2 == 0) { dp = new boolean[n][total / 2 + 1]; dfw(n - 1, total / 2); } System.out.println("impossible"); } static boolean dfw(int idx, int v) { if (v == 0) { System.out.println("possible"); System.exit(0); } if (v < 0 || idx < 0) { return true; } if (!dp[idx][v]) { dp[idx][v] = (dfw(idx - 1, v) & dfw(idx - 1, v - weights[idx])); } return true; } } class Utilities { static String arrayToLineString(Object[] arr) { return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n")); } static String arrayToLineString(int[] arr) { return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new)); } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); StringBuilder sb = new StringBuilder(); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public int[] nextIntArray() throws Exception { return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray(); } public String next() throws Exception { while (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }