import java.util.Arrays; import java.util.LinkedList; import java.util.Queue; import java.util.Scanner; public class Main { public static boolean dfs(int deep, int N, int purpose, int current, boolean[] used){ if(purpose == current){ return true; }else if(purpose > current){ return false; }else if(deep >= N){ return false; } for(int i = deep; i < N; i++){ if(!used[i]){ used[i] = true; if(dfs(deep + 1, N, purpose, current, used)){ return true; } used[i] = false; } } return false; } public static void main(String[] args){ Scanner sc = new Scanner(System.in); final int N = sc.nextInt(); int[] arr = new int[N]; for(int i = 0; i < N; i++){ arr[i] = -sc.nextInt(); } Arrays.sort(arr); for(int i = 0; i < N; i++){ arr[i] = -arr[i]; } final int purpose = Arrays.stream(arr).sum() / 2; System.out.println(dfs(0, N, purpose, 0, new boolean[N]) ? "possible" : "impossible"); } }