#include <iostream>
#include <vector>

using namespace std;

int n;
vector<int> w;
int weightSum = 0;
int weightSumHalf;

bool traverse(int position, int sum)
{
	sum += w[position];
	if (sum < weightSumHalf) {
		for (int i = position + 1; i < n; ++i) {
			if (traverse(i, sum)) {
				return true;
			}
		}
		return false;
	} else if (sum > weightSumHalf) {
		return false;
	} else {
		return true;
	}
}

int main(int argc, char* argv[])
{
	cin >> n;
	w.resize(n);
	for (int i = 0; i < n; ++i) {
		cin >> w[i];
		weightSum += w[i];
	}
	if (weightSum % 2 == 1) {
		cout << "impossible" << endl;
		return 0;
	}
	weightSumHalf = weightSum / 2;

	if (traverse(0, 0)) {
		cout << "possible" << endl;
	} else {
		cout << "impossible" << endl;
	}

	return 0;
}