#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <queue>
#include <utility>
#include <deque>
#include <iterator>
#include <cstdlib>
#include <cmath>
#include<map>
#include<tuple>
#include<iomanip>
using namespace std;
using ll = long long;
typedef pair<int, int> edge;

int main() {
	int n, w[109], sum = 0;
	int dp[109][10009];
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> w[i];
		sum += w[i];
	}
	if (sum % 2 != 0) {
		cout << "impossible" << endl;
		return 0;
	}
	vector<int> s;
	s.push_back(0);
	for (int i = 1; i <= n; i++) {
		int q = s.size();
		for (int j = 0; j < q; j++) {
			int p = s[j] + w[i];
			if (p * 2 == sum) {
				cout << "possible" << endl;
				return 0;
			}
			s.push_back(p);
		}
	}
	cout << "impossible" << endl;
}