package src;

import java.util.*;
public class A{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		int sum=0;
		int[] in = new int[s.nextInt()];
		for(int i=0;i<in.length;i++)
			sum+=(in[i]=s.nextInt());
		if(sum%2!=0) {
			System.out.println("impossible");
			return;
		}
		Arrays.sort(in);
		boolean[] dp = new boolean[10001];
		dp[0]=true;
		for(int i:in) {
			for(int d=dp.length-1;d>=0;d--) {
				if(dp[d])
					dp[d+i]=true;
			}
		}
		System.out.println(dp[sum/2]?"possible":"impossible");
	}
}