import java.util.Scanner;

public class Main {
	
	static int N;
	static int list[];
	static boolean flag[];
	static int target;
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		N = scan.nextInt();
		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 {
			target = sum / 2;
			flag = new boolean[N];
			while(true) {
				if( solve(0, 0) ) {
					boolean savedFlag[] = flag.clone();
					if(solve(0, 0)) {
						System.out.println("possible");
						break;
					} else {
						flag = savedFlag;
					}
				} else {
					System.out.println("impossible");
					break;
				}
			}
		}
	}
	
	static boolean solve(int now, int firstI) {
		if(now > target) return false;

		if(now == target) {
			return true;
		}
		
		boolean find = false;
		for(int i=firstI; i<N; i++) {
			if(!flag[i]) {
				flag[i] = true;
				find = solve(now+list[i], i+1);
				if(find) break;
				flag[i] = false;
			}
		}
		return find;
	}
}