import java.util.*;

class Yuki4{


	static boolean myFullSearch(int[] w,int count,int sum,int n,int purpose) {
		boolean left=false,right=false;
		sum += w[count];
		if(sum*2 == purpose){
			return true;
		}else if(count < n){
			left = myFullSearch(w,count+1,sum,n,purpose);
			right = myFullSearch(w,count+1,sum-w[count],n,purpose);
			if(left==true || right ==true) return true;
		}

		return false;
	}


	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		int n = stdIn.nextInt();
		int[] weight = new int[n+1];
		int sum=0;
		for(int i=0;i<n;i++){
			weight[i] = stdIn.nextInt();
			sum += weight[i];
		}

		boolean answer = myFullSearch(weight,0,0,n,sum);
		String a;
		if(answer==true){
			a="possible";
		}
		else{
			a="impossible";
		}
		System.out.println(a);




	}
}