#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) {
		set<int> dp;
		dp.insert(0);
		for (int i = 0; i < N; i++) {
			set<int> dp_next;
			for (int d : dp) {
				dp_next.insert(d);
				int next = d + W[i];
				if (next == sum / 2) {
					return "possible";
				}
				if (next < sum / 2) {
					dp_next.insert(next);
				}
			}
			dp = dp_next;
		}
	}
	return "impossible";
}

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