#include <iostream>
#include <vector>
#include <numeric>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

int main() {
	int n;
	cin >> n;
	vector<int> w(n);
	rep(i, n) cin >> w[i];

	int sum = accumulate(w.begin(), w.end(), 0);
	if (sum % 2 == 1) {
		cout << "impossible\n";
		return 0;
	}

	vector<vector<bool>> dp(n + 1, vector<bool>(sum / 2 + 1, false));
	dp[0][0] = true;
	rep(i, n) {
		rep(j, sum / 2 + 1) {
			dp[i + 1][j] = dp[i][j];
			if (j - w[i] >= 0) {
				dp[i + 1][j] = dp[i + 1][j] || dp[i][j - w[i]];
			}
		}
	}
	
	if (dp[n][sum / 2]) {
		cout << "possible\n";
	}
	else {
		cout << "impossible\n";
	}

	return 0;
}