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