import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		int[] W = new int[N];
		for (int i = 0; i < N; i++) {
			W[i] = scanner.nextInt();
		}

		System.out.println(f(W));
	}

	private static String f(int[] w) {
		int sum = 0;
		for (int i = 0; i < w.length; i++) {
			sum += w[i];
		}
		if (sum % 2 == 1) {
			return "impossible";
		}
		int target = sum / 2;

		boolean[][] dp = new boolean[target + 1][w.length + 1];
		dp[0][0] = true;

		for (int i = 0; i < target; i++) {
			for (int j = 0; j < w.length; j++) {
				if (dp[i][j]) {
					if (i + w[j] <= target) {
						dp[i + w[j]][j + 1] = true;
					}
					dp[i][j + 1] = true;
				}
			}
		}

		return dp[target][w.length] ? "possible" : "impossible";
	}

}