import java.util.Scanner;

public class No4 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        int[] w = new int[n];
        int sum = 0;
        for (int i = 0; i < n; i++) {
            w[i] = Integer.parseInt(sc.next());
            sum += w[i];
        }

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

        int half = sum / 2;
        boolean[] dp = new boolean[half];
        dp[0] = true;

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < half; j++) {
                if(dp[j] && j+w[i] < half){
                    dp[j+w[i]] = true;
                }
            }
        }
        if(dp[half-1]){
            System.out.println("possible");
        }else{
            System.out.println("impossible");
        }
    }
}