import java.util.Arrays;
import java.util.Scanner;

/**
 * Created by whiled on 17/05/04.
 */
public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        int[] v = new int[N];
        for (int i = 0; i < N; i++) v[i] = scan.nextInt();

        int sum = Arrays.stream(v).sum();
        int comp = sum / 2;
        if (sum % 2 == 1) {
            System.out.println("impossible");
            return;
        }


        boolean[] res = new boolean[sum + 1];

        for (int i = 0; i < res.length; i++) res[i] = false;
        res[0] = true;

        for (int i = 0; i < N; i++) {
            for (int j = res.length - 1; j > -1; j--) {
                if (res[j]) res[j + v[i]] = true;
            }
        }

        if (res[comp]) System.out.println("possible");
        else System.out.println("impossible");
    }
}