#include <iostream>
using namespace std;

int n,w[100];
bool map[100][100];
bool check(const int keep,int pos){
	for(int v = 0,i = pos;i < n;i++){
		if(!map[i][w[i]]){
			v = keep - w[i];
			map[i][w[i]] = true;
			if(v == 0){
				return true;
			} else if(v < 0){
				return false;
			} else if(check(v,i + 1)){
				return true;
			}
		}
	}
	return false; 
}

int main(void){
	int i,all = 0;
	cin >> n;
	for(i = 0;i < n;i++){
		cin >> w[i];
		all += w[i];
	}
	if(all % 2 != 0){
		cout << "impossible" << endl;
		return 0;
	}
	for(i = 0;i < n;i++){
		for(int t = i+1;t < n;t++){
			 if(w[i] < w[t]){
				int z = w[t];
				w[t] = w[i];
				w[i] = z;
			}
		}
	}
	if(check(all/2,0)){
		cout << "possible" << endl;
		return 0;	
	} 
	cout << "impossible" << endl;
}