package src;

import java.util.*;
public class A{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		int a=0,b=0;
		int[] in = new int[s.nextInt()];
		for(int i=0;i<in.length;i++) in[i]=s.nextInt();
		Arrays.sort(in);
		for(int i=in.length-1;i>=0;i--) {
			if(a<b)
				a+=in[i];
			else
				b+=in[i];
		}
		System.out.println(a==b?"possible":"impossible");
	}
}