import java.util.Scanner;
class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int[] data = new int [sc.nextInt()];
		
		int num = 0;
		for(int i = 0 ; i < data.length ; i++) {
			data[i] = sc.nextInt();
			num += data[i];
		}
		
		if(num % 2 == 1) {
			System.out.println("impossible");
			return;
		}
		
		num /= 2;
		
		Boolean [][] flug = new Boolean [101][10001];
		
		for(int i = 0 ; i < 101 ; i++)
			for(int j = 0 ; j < 10001 ; j++)
				flug[i][j] = false;
		
		flug[0][0] = true;
		
		for(int i = 0 ; i < data.length ; i++) {
			for(int j = 0 ; j < 10000 ; j++) {
				if(flug[i][j] == true) {
					flug[i + 1][j + data[i]] = true;
					flug[i + 1][j] = true;
				}
			}
		}
		
		if(flug[data.length][num] == true)System.out.println("possible");
		else System.out.println("impossible");
	}
}