#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 Increase_Binary(std::bitset<100> &a) {

	unsigned int i = 0;
	while (1) {
		if (a[i] == 0) {
			a[i] = 1;
			break;
		}
		else {
			a[i] = 0;
			i++;
		}
	}
}

int main(void) {

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

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

	if (W.sum() % 2 != 0) {
		std::cout << "impossible" << std::endl;
		return 0;
	}

	int half = N / 2, count = 0, sum = 0, compare = W.sum() / 2;
	std::bitset<100> flg;
	while (1) {
		Increase_Binary(flg);
		count = flg.count();
		if (count == N) { break; }
		if (count > half) { continue; }

		sum = 0;
		for (int i = 0; i < N; i++) {
			if (flg[i]) { sum += W[i]; }
		}

		if (sum == compare) {
			std::cout << "possible" << std::endl;
			return 0;
		}
	}

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

}