#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <set>
#include <cmath>

using namespace std;


int main(){
	int N;
	cin >> N;
	vector<int> W(N);
	int sum = 0;
	for(int i=0; i<N; i++){
		cin >> W[i];
		sum += W[i];
	}

	set<int> dp;
	for(int i=0; i<N; i++){
		vector<int> push;
		for(auto itr=dp.begin(); itr!=dp.end(); itr++){
			push.push_back(*itr + W[i]);
		}
		for(auto itr=push.begin(); itr!=push.end(); itr++){
			dp.insert(*itr);
		}
		dp.insert(W[i]);
	}

	if(sum%2==0 && dp.find(sum/2) != dp.end()){
		cout << "possible " << endl;
	}else{
		cout << "impossible " << endl;
	}
	return 0;
}