/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		
		// your code goes here
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int w[] = new int[n];
		for (int j = 0; j < n; j++) {
			w[j] = sc.nextInt();
		}
		sc.close();
		
		Arrays.sort(w);
		int sum1 = w[n-1];
		int sum2 = 0;
		for (int i = 1; i < n;i++) {
			if (sum1 < sum2) {
				sum1 += w[n-1-i];
			} else {
				sum2 += w[n-1-i];
			}
		}
		System.out.println((sum1 == sum2) ? "possible" : "impossible");
	}
}