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

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::vector<int> dp(1, 0);

	for (int i = 0; i < weight.size(); i++) {
		for (int j = dp.size() - 1; j >= 0; j--) {
			dp.push_back(dp[j] + weight[i]);
		}
	}

	if(std::find(dp.begin(), dp.end(), sum) != dp.end()) {
		std::cout << "possible" << std::endl;
	} else {
		std::cout << "impossible" << std::endl;
	}

	return 0;
}