#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
typedef pair<int, int> pii;
int N;
vector<pii> dp[101];
string ans = "impossible";
int main(void) {
	cin >> N;
	dp[0].push_back(pii(0, 0));
	for (int n = 1; n <= N; ++n) {
		int W; cin >> W;
		for (size_t idx = 0U; idx < dp[n - 1].size(); ++idx) {
			pii pre = dp[n - 1][idx];
			dp[n].push_back(pii(pre.first + W, pre.second));
			dp[n].push_back(pii(pre.first, pre.second + W));
		}
	}
	for (size_t idx = 0U; idx < dp[N].size(); ++idx) {
		if (dp[N][idx].first == dp[N][idx].second) ans = "possible";
	}
	cout << ans << endl;
	return 0;
}