#include <iostream>
#include <vector>
#include <string>
#include <numeric>
#include <algorithm>
using namespace std;
typedef pair<int, int> pii;
int N;
bool dp[10001][10001];
string ans = "impossible";
int main(void) {
	cin >> N;
	dp[0][0] = true;
	const int max = 100 * N;
	for (int n = 0; n < N; ++n) {
		int W; cin >> W;
		for (int l = max; l >= 0; --l) {
			for (int r = max; r >= 0; --r) {
				if (max < l + W || max < r + W) continue;
				if (dp[l][r]) {
					dp[l][r + W] = dp[l + W][r] = true;
					dp[l][r] = false;
				}
			}
		}
	}
	for (int n = 1; n <= max; ++n) {
		if (dp[n][n]) ans = "possible";
	}
	cout << ans << endl;
	return 0;
}