#include <iostream>
#include <vector>
#include <set>

using namespace std;

int N;
int W[100];

bool input(istream& in)
{
	in >> N;
	for (int i = 0; i < N; i++) {
		in >> W[i];
	}
	return true;
}

const char *resolve()
{
	int sum = 0;
	for (int i = 0; i < N; i++) {
		sum += W[i];
	}
	if (sum % 2 == 0) {
		vector<int> dp(sum / 2);
		dp[0] = 1;
		for (int i = 0; i < N; i++) {
			for (int d = 0; d < sum / 2; d++) {
				if (dp[d]) {
					int next = d + W[i];
					if (next == sum / 2) {
						return "possible";
					}
					if (next < sum / 2) {
						dp[next] = 1;
					}
				}
			}
		}
	}
	return "impossible";
}

int main(int argc, char **argv)
{
	while (input(cin)) {
		cout << resolve() << endl;
	}
	return 0;
}