package yukicoder;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {

	public static void main(String[] args) {
		BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));

		try {
			int N = Integer.parseInt(buff.readLine());
			String[] box = buff.readLine().split(" ");
			int[] w = new int[N];

			for (int i = 0; i < N; ++i) {
				w[i] = Integer.parseInt(box[i]);
			}
			Arrays.sort(w);

			int left = 0, right = 0, index = N - 1;
			while (N-- > 0) {
				if (left < right) {
					left += w[index--];
				} else {
					right += w[index--];
				}
			}

			if (right == left) {
				System.out.println("possible");
			} else {
				System.out.println("impossible");
			}
		} catch (Exception e) {
			e.getStackTrace();
		}
	}

}