import java.util.Arrays;
import java.util.Scanner;

public class Main{

	public static void main(String[] args) {
		Main main=new Main();
		main.run();
	}

	void run() {

		Scanner sc=new Scanner(System.in);

		int n=sc.nextInt();





		int[] dp= new int[10101];
		
		Arrays.fill(dp,1);
		
		int sum=0;


		for(int i=0;i<n;i++) {
			int buf=sc.nextInt();
			sum+=buf;
			
			for(int j=10000;j>0;j--) {
				dp[j+buf]+=dp[j];
			}

		}

		if(sum%2==1 || dp[sum/2]==1) {
			System.out.println("impossible");
		}else {
			System.out.println("possible");
		}

	}

}