import java.util.*;
 

public class Main {
	static int sum=0;
	static int[] omori;
	static boolean dfs(int now,int sum1,int kazu){
		if(now==kazu){
			if(sum1==sum/2){
				return true;
			}else{
				return false;
			}			
		}
		if(dfs(now+1,sum1,kazu)) return true;
		if(dfs(now+1,sum1+omori[now],kazu)) return true;
		return false;
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N=sc.nextInt();
		 omori = new int[N];
		for(int i=0;i<N;i++){
			int temp=sc.nextInt();
			sum+=temp;
			omori[i]=temp;
		}
		if(!(sum%2==0)){
			System.out.println("impossible");
			return;
		}
		if(dfs(0,0,N)){
			System.out.println("possible");
		}else{
			System.out.println("impossible");
		}
		
	}
}