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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int[] weights = new int[n];
        int total = 0;
        for (int i = 0; i < n; i++) {
            weights[i] = sc.nextInt();
            total += weights[i];
        }
        if (total % 2 == 1) {
            System.out.println("impossible");
            return;
        }
        total /= 2;
        TreeSet<Integer> ans = new TreeSet<>();
        ans.add(0);
        for (int x : weights) {
            Integer key = total - x + 1;
            while ((key = ans.lower(key)) != null) {
                ans.add(key + x);
            }
        }
        if (ans.contains(total)) {
            System.out.println("possible");
        } else {
            System.out.println("impossible");
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}