import java.io.*; import java.util.*; class Main4 { public static boolean check (int[] nums, int target) { boolean[] dp = new boolean[target + 1]; Arrays.sort(nums); dp[0] = true; for (int i = 0; i < nums.length; i++) { for (int j = 0; j <= target; j++) { if (!dp[j]) continue; if (nums[i] + j <= target) dp[j = nums[i] + j] = true; else break; } } return dp[target]; } public static void main (String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int n = Integer.parseInt(br.readLine()); int target = 0; int[] nums = new int[n]; String[] str = br.readLine().split(" "); for (int i = 0; i < n; i++) { nums[i] = Integer.parseInt(str[i]); target += nums[i]; } if (target % 2 == 1) System.out.println("impossible"); else { target /= 2; System.out.println(check(nums, target) ? "possible" : "impossible"); } } }