#include <iostream>

using namespace std;

bool dp[110][5010];

int main() {
	int n;
	int w[110];
	int sum = 0;
	cin >> n;
	for (int i = 1; i <= n; i++) {
		cin >> w[i];
		sum += w[i];
	}
	if (sum % 2 == 1) {
		cout << "impossible";
		return 0;
	}
	sum /= 2;
	for (int i = 0; i <= n; i++) {
		dp[0][i] = false;
		dp[i][0] = true;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= sum; j++) {
			if (dp[i - 1][j - w[i]] == true || dp[i - 1][j] == true) {
				dp[i][j] = true;
			}
			else {
				dp[i][j] = false;
			}
		}
	}
	if (dp[n][sum]) {
		cout << "possible";
	}
	else {
		cout << "impossible";
	}
}