import java.io.BufferedReader; import java.io.InputStreamReader; public class No004 { static long balance; static long sum; public static void main(String[] args) { try { BufferedReader br = new BufferedReader(new InputStreamReader( System.in)); int N = Integer.parseInt(br.readLine()); long[] W = strTointArray(br.readLine()); for (long l : W) { balance = balance + l; } if (balance % 2 != 0) { System.out.println("impossible"); } else { balance = balance / 2; if (dfs(W, 0, -1)) { System.out.println("possible"); } else { System.out.println("impossible"); } } } catch (Exception e) { System.err.println("Error:" + e.getMessage()); } } static boolean dfs(long[] W, long w, int i) { if (balance == sum) { return true; } if (balance < sum) { return false; } if (i == W.length) { return false; } sum = sum + w; if (dfs(W, W[i], i + 1)) { return true; } if (dfs(W, 0, i + 1)) { return true; } return false; } static long[] strTointArray(String S) { String[] strArray = S.split(" "); long[] longArray = new long[strArray.length]; for (int i = 0; i < strArray.length; i++) { longArray[i] = Long.parseLong(strArray[i]); } return longArray; } }