import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int sum = 0;
		int[] v = new int[n+1];


		for(int i = 1; i < n+1; i++){
			v[i] = scanner.nextInt();
			sum += v[i];
		}

		if(sum % 2 == 1){
			System.out.println("impossible");
			return;
		}

		int[][] dp = new int[n+1][sum/2+1];

		for(int i = 1; i < n+1; i++){
			for(int j = 1; j < sum/2+1; j++){
				if(j >= v[i]){
					dp[i][j] = Math.max(dp[i-1][j], dp[i-1][j-v[i]] + v[i]);
				}else {
					dp[i][j] = dp[i-1][j];
				}
			}
		}

		if(dp[n][sum/2] == sum/2){
			System.out.println("possible");
		}else {
			System.out.println("impossible");
		}
	}
}