import java.io.PrintWriter;
import java.util.Scanner;

public class Main {
	static int mod=1000003;
	public static void main(String[] args) throws Exception {
		PrintWriter pw=new PrintWriter(System.out);
		Scanner sc=new Scanner(System.in);
		
		int n=sc.nextInt();
		int sum=0;
		int[] w=new int[n];
		for(int i=0;i<n;i++){
			int tmp=sc.nextInt();
			sum+=tmp;
			w[i]=tmp;
		}
		if(sum%2!=0){
			pw.println("impossible");
			pw.close();
			return;
		}
		boolean[] check=new boolean[10001];
		check[0]=true;
		for(int i=0;i<n;i++){
			for(int j=0;j+w[i]<10001;j++){
				if(check[j]&&!check[j+w[i]]){
					check[j+w[i]]=true;
				}
			}
		}
		if(check[sum/2]){
			pw.print("possible");
		}else{
			pw.print("impossible");
		}
		pw.close();
		sc.close();
	} 
}