import java.util.*;
import java.math.*;

public class Main {
    static boolean[][] dp;
    static boolean[][] used;
    static int[] arr;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int total = 0;
        arr = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            arr[i] = sc.nextInt();
            total += arr[i];
        }
        if (total % 2 == 1) {
            System.out.println("impossible");
            return;
        }
        dp = new boolean[n + 1][total / 2 + 1];
        used = new boolean[n + 1][total / 2 + 1];
        if (dfw(n, total / 2)) {
            System.out.println("possible");
        } else {
            System.out.println("impossible");
        }
    }
    
    static boolean dfw(int idx, int value) {
        if (value < 0) {
            return false;
        }
        if (value == 0) {
            return true;
        }
        if (idx == 0) {
            return false;
        }
        if (used[idx][value]) {
            return dp[idx][value];
        }
        used[idx][value] = true;
        dp[idx][value] = (dfw(idx - 1, value) | dfw(idx - 1, value - arr[idx]));
        return dp[idx][value];
    }
}