import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int N = Integer.parseInt(br.readLine());

        String[] strW = br.readLine().split(" ");

        int[] W = new int[strW.length];
        int sum = 0;
        for (int i = 0; i < strW.length; i++) {
            W[i] = Integer.parseInt(strW[i]);
            sum += W[i];
        }

        if (sum % 2 != 0) {
            System.out.println("impossible");
            return;
        }

        int[] d = new int[sum / 2 + 1];

        Arrays.fill(d, Integer.MAX_VALUE);
        d[0] = -1;

        for (int i = 0; i < W.length; i++) {
            int tmpW = W[i];
            for (int j = 0; j < d.length - tmpW; j++) {
                if (d[j] != Integer.MAX_VALUE) {
                    if (sum / 2 == j + tmpW) {
                        System.out.println("possible");
                        return;
                    } else if (j + tmpW < d.length && d[j] != i) {
                        d[j + tmpW] = i;
                    }
                }
            }
        }

        System.out.println("impossible");
    }
}