import java.util.*;
 

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N=sc.nextInt();
		int sum=0;
		int[] 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;
		}
		boolean[] check = new boolean[10001];
		check[0]=true;
		for(int i=0;i<N;i++){
			for(int j=10000;j>=0;j--){
				if(check[j]&&!check[j+omori[i]]){
					check[j+omori[i]]=true;
				}
			}
		}
		if(check[sum/2]){
			System.out.println("possible");
		}else{
			System.out.println("impossible");
		}
	}
}