#include <iostream>

using namespace std;

bool dp[10005];

int main() {
	int n, w[105],sum=0;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> w[i];
		sum += w[i];
	}
	if (sum % 2 == 1) {
		cout << "impossible";
		return 0;
	}
	dp[0] = true;
	for (int i = 1; i <=sum/2; i++) {
		dp[i] = false;
		for (int j = 0; j < n; j++) {
			if (i - w[j] < 0)continue;
			if (dp[i - w[j]]) {
				dp[i] = true; break;
			}
		}
	}
	if (dp[sum / 2])
		cout << "possible";
	else
		cout << "impossible";
	return 0;
}