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

public class Main {
    static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        int N = in.nextInt();
        int[] w = new int[N];
        int sum = 0;

        for(int i = 0; i < N; i++){
            w[i] = in.nextInt();
            sum += w[i];
        }

        if(sum % 2 == 1){
            System.out.println("impossible");
            return;
        }

        boolean[] dp = new boolean[sum / 2 + 1];
        Arrays.fill(dp, false);
        dp[0] = true;
        for(int i = 0; i < dp.length; i++){
            for(int j = 0; j < w.length; j++){
                if(dp[i] && i + w[j] < dp.length){
                    dp[i + w[j]] = true;
                }
            }
        }
        if(dp[N]){
            System.out.println("possible");
        }else{
            System.out.println("impossible");
        }
    }
}