#include <bits/stdc++.h>

using namespace std;

int n,half;
vector<int> w;
bool isHalf(int m, int sum) {
	if (sum == half) {
		return true;
	}
	else if (sum > half) {
		return false;
	}
	else {
		for (int i = m + 1; i < n;i++) {
			if (isHalf(i, sum + w[m])) {
				return true;
			}
		}
		return false;
	}
}
int main() {
	cin >> n;
	w.resize(n);
	half = 0;
	for (int i = 0;i < n;i++) {
		cin >> w[i];
		half += w[i];
	}
	if (half % 2 != 0) {
		cout << "impossible" << endl;
		return 0;
	}
	half /= 2;
	sort(w.begin(), w.end(), greater<int>());
	for (int i = 0;i < n;i++) {
		if (isHalf(i, 0)) {
			cout << "possible" << endl;
			return 0;
		}
	}
	cout << "impossible" << endl;
	return 0;
}