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;
    }
}