#include <iostream>
#include <vector>

int main(int argc, char **argv) {
	int n = -1;
	int w = -1;
	int amount_w = 0;
	int half_w = 0;
	std::vector<int> ws;

	std::cin >> n;
	for (int i = 0; i < n; i++) {
		std::cin >> w;
		amount_w += w;
		ws.push_back(w);
	}

	half_w = amount_w / 2;
	if (amount_w % 2 != 0) {
		std::cout << "impossible\n";
		return 0;
	}

	bool checks[amount_w + 1] = { false };

	checks[0] = true;

	for (int i = 0; i < n; i++) {
		for (int j = 0; j <= amount_w; j++) {
			if (!checks[j]) {
				break;
			}
			checks[j + ws.at(i)] = true;
		}
	}

	if (checks[half_w]) {
		std::cout << "possible\n";
	} else {
		std::cout << "impossible\n";
	}
	return 0;
}