import java.util.*;

public class Main {
	
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		boolean ok[]=new boolean[10001];
		ok[0]=true;
		int sum=0;
		for(int i=0;i<n;i++){
			int x=sc.nextInt();
			
			for(int j=0;j<=sum;j++){
				if(ok[j])ok[j+x]=true;
			}
			sum+=x;
		}
		String s="";
		if(sum%2==1)s="impossible";
		else {
			if(ok[sum/2])s="possible";
			else s="impossible";
		}
		System.out.println(s);
	}}