package no004;

import java.util.Scanner;

public class Main {

	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];
		}
		if (sum % 2 == 1) {
			System.out.println("impossible");
			return;
		}
		sum /= 2;
		boolean[][] dp = new boolean[n+1][sum+1];
		dp[0][0] = true;
		for(int i=1;i<=n;i++) {
			for(int j=0;j<=sum;j++) {
				dp[i][j] = dp[i-1][j];
				if (j - w[i-1] >= 0) {
					dp[i][j] |= dp[i-1][j-w[i-1]];
				}
			}
		}
		System.out.println(dp[n][sum] ? "possible" : "impossible");
	}

}