import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	
	// どんな個数でも錘の合計の半分の重さを達成できれば, 残りの錘も半分の重さである (重さが半分に割り切れれば).
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		
		int[] arr = new int[N];
		for(int i = 0; i < N; i++){
			arr[i] = sc.nextInt();
		}
		final int sum = Arrays.stream(arr).sum();
		
		if(sum % 2 != 0){
			System.out.println("impossible");
		}else{
			boolean[] DP = new boolean[sum + 1];
			
			DP[0] = true;
			for(int i = 0; i < N; i++){
				for(int k = sum - arr[i]; k >= 0; k--){
					if(DP[k]){
						DP[k + arr[i]] = true;
					}
				}
			}
			
			System.out.println(DP[sum / 2] ? "possible" : "impossible");
		}
		
	}
	
}