#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
	int num;
	cin >> num;
	vector<int> w;
	int balance_1 = 0, balance_2 = 0;
	for (int i = 0;i < num;i++) {
		int temp; cin >> temp;
		balance_1 += temp;
		w.push_back(temp);
	}
	sort(w.begin(), w.end());

	for (int i = 0; i < num/2 ; i++) {
		balance_1 -= w[num - 1 - i];
		balance_2 += w[num - 1 - i];

		if (balance_1 == balance_2) {
			cout << "possible" << endl;
			return 0;
		}
	}

	cout << "impossible" << endl;

	return 0;
}