import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;


public class Main_yukicoder4 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        int[] w = new int[n];
        int sum = 0;
        for (int i = 0; i < n; i++) {
        	w[i] = sc.nextInt();
        	sum += w[i];
        }

        boolean flag = false;
        if (sum % 2 == 0) {
        	Set<Integer> hs = new HashSet<Integer>();
        	
        	for (int i = 0; i < n; i++) {
        		for (int e : hs.toArray(new Integer[0])) {
        			hs.add(w[i] + e);
        		}
        		hs.add(w[i]);
        		
        		if (hs.contains(sum / 2)) {
        			flag = true;
        			break;
        		}
        	}
        }

        if (flag) {
        	System.out.println("possible");
        } else {
        	System.out.println("impossible");
        }
        
        sc.close();
    }
}