#include<iostream>
#include<vector>
#include<algorithm>
#include<numeric>
#include<set>

int main() {
	int n;
	std::cin >> n;

	std::vector<int> weight(n);
	for (int i = 0; i < n; i++) {
		std::cin >> weight[i];
	}

	int sum = std::accumulate(weight.begin(), weight.end(), 0);

	// 重さが奇数では天秤が平らになることはない
	if (sum % 2 == 1) {
		std::cout << "impossible" << std::endl;
		return 0;
	}

	sum /= 2; // この重さを作れたら勝ち

	std::set<int> dp;
	dp.insert(0);

	for (int i = 0; i < weight.size(); i++) {
		for (auto it = dp.rbegin(); it != dp.rend(); it++) {
			int num = *it;
			if (num + weight[i] == sum) {
				std::cout << "possible" << std::endl;
				return 0;
			}
			if (num + weight[i] > sum) continue;
			dp.insert(num + weight[i]);
		}
	}

	std::cout << "impossible" << std::endl;


	return 0;
}