#include <iostream>
#include <vector>

using namespace std;

int main(int argc, char* argv[])
{
	int n;
	cin >> n;
	vector<int> w(n);
	int weightSum = 0;
	for (int i = 0; i < n; ++i) {
		cin >> w[i];
		weightSum += w[i];
	}
	if (weightSum % 2 == 1) {
		cout << "impossible" << endl;
		return 0;
	}
	
	vector<bool> weightPossible(10001);
	weightPossible[0] = true;
	
	for (int i = 0; i < n; ++i) {
		for (int j = 10000; j >= w[i]; --j) {
			if (weightPossible[j - w[i]]) {
				weightPossible[j] = true;
			}
		}
	}

	if (weightPossible[weightSum / 2]) {
		cout << "possible" << endl;
	} else {
		cout << "impossible" << endl;
	}

	return 0;
}