#include <bits/stdc++.h>

//const static double	de_PI	= 3.14159265358979323846;
//const static double	de_EPS	= 0.000001;
//const static int	de_MOD = 1000000007;
//const static int	de_MAX = 999999999;
//const static int	de_MIN = -999999999;

inline void Calc(const int &sum, const int &count, const int &idx, const std::vector<int> &W, const int &target) {

	if (sum == target) { 
		std::cout << "possible" << std::endl;
		exit(1);
	}

	if (count <= 0) { return; }
	if (idx >= static_cast<int>(W.size())) { return; }

	Calc(sum + W[idx], count - 1, idx + 1, W, target);
	Calc(sum, count, idx + 1, W, target);

}

int main(void) {

	//std::ifstream inf("123.txt");	std::cin.rdbuf(inf.rdbuf());

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

	int total = std::accumulate(W.begin(), W.end(), 0);
	if (total % 2 != 0) {
		std::cout << "impossible" << std::endl;
		return 0;
	}

	Calc(0, N / 2, 0, W, total / 2);
	std::cout << "impossible" << std::endl;

}