import java.util.Scanner;

public class Main {
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int list[] = new int[N];
		int sum = 0;
		for(int i=0; i<N; i++) {
			list[i] = scan.nextInt();
			sum += list[i];
		}
		scan.close();
		
		if(sum % 2 == 1) {
			System.out.println("impossible");
		} else {
			int target = sum / 2;
			boolean dp[] = new boolean[sum+1];
			dp[list[0]] = true;
			
			for(int i=1; i<N; i++) {
				for(int j=sum; j>=1; j--) {
					if(dp[j]) dp[j+list[i]] = true;
				}
				dp[list[i]] = true;
			}
			
			if(dp[target]) {
				System.out.println("possible");
			} else {
				System.out.println("impossible");
			}
		}
    }	
}