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

class Main4 {
	
	public static boolean check (int[] nums, int target) {
		boolean[] dp = new boolean[target + 1];
		
		Arrays.sort(nums);
		dp[0] = true;
		for (int i = 0; i < nums.length; i++) {
			for (int j = 0; j <= target; j++) {
				if (!dp[j]) continue;
				if (nums[i] + j <= target)
					dp[j = nums[i] + j] = true;
				else
					break;
			}
		}
		return dp[target];
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
		int target = 0;
		int[] nums = new int[n];
		String[] str = br.readLine().split(" ");
		for (int i = 0; i < n; i++) {
			nums[i] = Integer.parseInt(str[i]);
			target += nums[i];
		}
		if (target % 2 == 1)
			System.out.println("impossible");
		else {
			target /= 2;
			System.out.println(check(nums, target) ? "possible" : "impossible");
		}
	}
}