#include <iostream>

using namespace std;

int N;
int W[100];
bool dp[5001];

int main() {
	cin >> N;
	int sum = 0;
	for (int i = 0; i < N; i++) {
		cin >> W[i];
		sum += W[i];
	}
	if (sum % 2) {
		cout << "impossible" << endl;
	} else {
		int target = sum / 2;
				for (int i = 0; i <= target; i++) {
					dp[i] = false;
				}
				dp[0] = true;
				for (int i = 0; i < N; i++) {
					for (int j = target - W[i]; j >= 0; j--) {
						if (dp[j]) {
							dp[j + W[i]] = true;
						}
					}
				}
				cout << (dp[target] ? "possible" : "impossible") << endl;
	}
	return 0;
}