#include <iostream>
#include <vector>
#include <numeric>

using namespace std;

bool possibles[101][10001] = { false }; // [index of weights][weight]

int main() {
	int n;
	cin >> n;
	vector<int> w(n + 1);
	for (int i = 0; i < n; ++i) {
		cin >> w[i + 1];
	}
	int sum = accumulate(w.begin(), w.end(), 0);
	if (sum % 2 == 1) {
		cout << "impossible" << endl;
		return 0;
	}
	possibles[0][0] = true;
	for (int i = 1; i <= n; ++i) {
		for (int k = 0; k <= sum / 2; ++k) {
			possibles[i][k] |= possibles[i - 1][k];
			possibles[i][k + w[i]] |= possibles[i - 1][k];
		}
	}
	cout << (possibles[n][sum / 2] ? "possible" : "impossible") << endl;
	return 0;
}