import java.util.Scanner;
public class Yuki4{
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int sum = 0;
		int[] w = new int[n];
		for(int i = 0;i<n;i++){
			w[i] = sc.nextInt();
		}
		for(int i = 0;i<n;i++){
			sum += w[i];
		}
		boolean[] ok = new boolean[sum+1];
		ok[0] = true;
		ok[sum] = true;
		if(sum % 2 != 0){
			System.out.println("impossible");
		}else{
			for(int i = 0;i<n;i++){
				for(int j = sum - w[i];j>=0;j--){
					if(ok[j])ok[j+w[i]] = true;
				}
			}
			if(ok[sum/2]){
				System.out.println("possible");
			}else{
				System.out.println("impossible");
			}
		}
	}
}